JP2018177826A - Core-shell particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soft resin particle good in handleability of a powder and excellent in solvent resistance.SOLUTION: The above described resin particle is a core-shell particle constituted by a core part and a shell part arranged on a surface thereof, and has volume average particle diameter of 3 μm to 150 μm, variation coefficent of particle diameter of 20% or more, 10%K value of any particle with particle diameter of 10±2 μm, 30±2 μm or 50±2 μm, nearest to the volume average particle diameter, satisfying following ranges. 10%K value of a particle with particle diameter of 10±2 μm is 830 N/mmor less. 10%K value of a particle with particle diameter of 30±2 μm is 680 N/mmor less. 10%K value of a particle with particle diameter of 50±2 μm is 320 N/mmor less.SELECTED DRAWING: None

Description

  The present invention relates to a core-shell particle composed of a core portion and a shell portion provided on the surface thereof.

  In recent years, resin-made fine particles having a size of several μm or more are used as a modifier in order to achieve high functionalization such as mechanical properties and optical properties of plastic products, paints, inks, adhesives and the like.

  As resin fine particles that can be used as the modifier, for example, Patent Document 1 discloses an inner layer mainly composed of an acrylic acid ester copolymer having a glass transition temperature of 0 ° C. or lower, and methacrylic acid having a glass transition temperature of 60 ° C. or higher Disclosed is an acrylic resin particle having a multilayer structure consisting of an outer layer mainly composed of an ester copolymer. Further, Patent Document 2 includes a rubber core made of a poly (meth) acrylate copolymer having a glass transition temperature of 0 ° C. or less having a three-dimensional crosslinked structure, and a hard resin having a glass transition temperature of 60 ° C. or more. A non-tacky shell core-shell bead thermoplastic polymer particle is disclosed.

Japanese Patent Application Publication No. 2003-128736 JP, 2007-070624, A

  When aiming at property modification of a soft resin composition, soft resin particles are suitably used. However, soft resin fine particles have the disadvantage of becoming rubbery and difficult to handle as powder. In order to powder such soft resin particles, a method such as adding silica particles is adopted, but since inorganic particles such as silica particles are not fixed to resin particles, the resin composition There is a problem that silica particles fall off in the object.

  Therefore, soft resin fine particles having a size of several μm or more added to the soft resin composition exhibit high softness that can follow deformation such as mixing of the resin composition without causing the above problem. Is required. Preferably, it is further required to have handleability as a powder and solvent resistance required when mixing with a resin composition. The particles disclosed in the above-mentioned Patent Documents 1 and 2 are polymer particles having a multilayer structure of an inner layer and an outer layer, and particles in which the inner layer is soft are disclosed. It was still insufficient.

  The present invention has been made focusing on the above circumstances and has a size of several μm or more and exhibits excellent softness, and preferably further to powder handling and solvent resistance. An object of the present invention is to provide an excellent core-shell particle. Hereinafter, the core-shell particles of the present invention may be referred to as "resin particles".

The core-shell particle of the present invention is composed of a core portion and a shell portion provided on the surface thereof, and has a volume average particle diameter of 3 μm to 150 μm and a variation coefficient of particle diameter of 20% or more. The 10% K value of particles having a particle diameter of 10 ± 2 μm, 30 ± 2 μm, or 50 ± 2 μm, which is closest to the volume average particle diameter, satisfies the following range.
10% K value of particles with a particle diameter of 10 ± 2 μm is 830 N / mm ² or less 10% K value of particles with a particle diameter of 30 ± 2 μm is 680 N / mm ² or less 10% K value of particles with particle diameter of 50 ± 2 μm is 320 N / Mm ² or less

  The core portion includes a copolymer having at least one of monofunctional (meth) acrylic monomer (C1) units and at least one of crosslinkable (meth) acrylic monomer (C2) units, and has a FOX formula The glass transition temperature Tg of the polymer consisting only of the monofunctional (meth) acrylic monomer (C1) calculated based on the basis is less than 0 ° C., and the shell part is a monofunctional (meth) acrylic monomer (S1) A heavy polymer comprising a copolymer having at least one unit and at least one unit of crosslinkable monomer (S2) and consisting only of the monofunctional (meth) acrylic monomer (S1) calculated based on the FOX formula It is preferable that the glass transition temperature Tg of a combination is 0 degreeC or more and less than 50 degreeC.

  The core-shell particle of the present invention is composed of a core portion and a shell portion provided on the surface thereof, wherein the core portion is at least one unit of monofunctional (meth) acrylic monomer (C1) units. And a polymer comprising only a copolymer having at least one of crosslinkable (meth) acrylic monomer (C2) units, and consisting of only the monofunctional (meth) acrylic monomer (C1) calculated based on the FOX formula A glass transition temperature Tg of less than 0.degree. C., and the shell portion is a copolymer having at least one monofunctional (meth) acrylic monomer (S1) unit and at least one crosslinkable monomer (S2) unit. The glass transition temperature Tg of the polymer consisting only of the monofunctional (meth) acrylic monomer (S1) calculated on the basis of the FOX formula including coalescence is at least 0 ° C. and less than 50 ° C. There also characterized by the.

  The monofunctional (meth) acrylic monomer (S1) in the shell portion is preferably an ester of an alcohol having 3 or more carbon atoms and (meth) acrylic acid.

  It is preferable that a crosslinkable (meth) acrylic monomer unit is contained as the crosslinkable monomer (S2) unit of the shell part.

  The crosslinkable (meth) acrylic monomer in the shell portion is preferably polyethylene glycol di (meth) acrylate in which the number of repeating ethylene glycol units is 2 or more.

  The crosslinkable monomer (S2) unit in the shell part is 1 to 50 parts by mass with respect to a total of 100 parts by mass of the monofunctional (meth) acrylic monomer (S1) unit and the crosslinkable monomer (S2) unit Is preferred.

  In the core-shell particles of the present invention, the proportion of particles passing through the 1.18 mm sieve is preferably 80% by mass or more.

The core-shell particles of the present invention preferably have a MEK swelling ratio of less than 3.0, which is calculated by the following solvent resistance test.
[Solvent resistance test]
Test tubes A and B with an inner diameter of 15 mm are prepared, 2.5 g of core-shell particles and 20 ml of a 1% by mass emulsifier aqueous solution are put in the test tube A, and 2.5 g of core-shell particles and 20 ml of methyl ethyl ketone are put in the test tube B The test tubes A and B are each dispersed with ultrasonic waves for 5 minutes and left for 12 hours, and then the height of the sedimented core-shell particles is measured, and the MEK swelling ratio is calculated according to the following formula (1).
MEK swelling ratio = (height of core-shell particles precipitated in methyl ethyl ketone (mm)) / (height of core-shell particles precipitated in aqueous emulsifier solution (mm)) (1)

  In the core-shell particles of the present invention, the ratio of the thickness of the shell portion to the volume average particle diameter is preferably 0.03 or more and 0.12 or less.

  The production method of the present invention is the production method of the above-mentioned core-shell particle, and a monofunctional (meth) acrylic monomer (C1), a crosslinkable (meth) acrylic monomer (C2), a polymerization initiator, a water soluble polymer Step 1 of reacting a suspension of a mixture containing a system dispersion stabilizer and an aqueous solvent to form a core polymerization part, and a monofunctional (meth) acrylic monomer (S1) unit, a crosslinkable monomer (S2) unit, A step 2 of contacting an emulsion liquid containing an emulsifier and an aqueous solvent with the reaction liquid containing the core polymerization part obtained in the above step 1 to form a shell polymerization part on the surface of the core polymerization part I assume.

  According to the present invention, it is possible to realize resin particles which exhibit excellent softness and preferably also excellent in powder handling and solvent resistance.

The core-shell particle of the present invention is a core-shell particle composed of a core portion and a shell portion provided on the surface thereof, and has a volume average particle diameter of 3 μm to 150 μm, and a variation coefficient of particle diameter of 20% or more The 10% K value of particles closest to the volume average particle diameter and having a particle diameter of 10 ± 2 μm, 30 ± 2 μm or 50 ± 2 μm is characterized in that the following range is satisfied. Hereinafter, the core-shell particles of the present invention will be described in detail.
10% K value of particles with a particle diameter of 10 ± 2 μm is 830 N / mm ² or less 10% K value of particles with a particle diameter of 30 ± 2 μm is 680 N / mm ² or less 10% K value of particles with particle diameter of 50 ± 2 μm is 320 N / Mm ² or less

  The present invention is directed to core-shell particles having a volume average particle diameter in the range of 3 μm to 150 μm. The lower limit of the volume average particle diameter is preferably 5 μm or more, more preferably 8 μm or more. The upper limit of the volume average particle size is preferably 120 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less.

  Further, the coefficient of variation (CV value) of the particle diameter of the core-shell particles of the present invention is 20% or more. When the core-shell particles are mixed with the resin composition as the CV value of the particle diameter of the core-shell particles is 20% or more, the packing density of the core-shell particles can be improved because the microparticles enter into the interstices of the particles.

  The coefficient of variation (CV value) of the particle diameter is a value determined by the following equation from the volume-based standard deviation of the particle diameter and the volume average particle diameter determined by measuring the particles with a particle size distribution analyzer using a Cole counter method. It is.

  Particle diameter variation coefficient (%) = (Standard deviation of particle diameter based on volume / Volume average particle diameter) x 100

  The lower limit of the particle diameter CV value is preferably 23% or more, more preferably 25% or more. The upper limit of the particle diameter CV value is, for example, 60% or less, preferably 55% or less, and more preferably 53% or less.

  The thickness of the shell portion is preferably 0.8 μm or more and 3.5 μm or less. By making the thickness of the shell part 0.8 μm or more, the effect of the shell part (especially, the improvement of the handling property of the powder and the solvent resistance, and the coexistence of the excellent softness and the handling property of the powder) Can be demonstrated more effectively. The thickness of the shell portion is more preferably 1.0 μm or more, still more preferably 1.3 μm or more. Further, by setting the thickness of the shell portion to 3.5 μm or less, it is preferable because the flexibility of the core portion can be easily exhibited. The thickness of the shell portion is more preferably 3.0 μm or less, still more preferably 2.5 μm or less, and still more preferably 2.0 μm or less.

  The lower limit of the ratio of the thickness of the shell portion to the volume average particle diameter of the core-shell particles (shell thickness / volume average particle diameter) is, for example, 0.02 or more, preferably 0.03 or more. It is 12 or less, preferably 0.10 or less.

  In the core-shell particles of the present invention, the compressive elastic modulus at the initial stage of deformation, which can be used as an index of softness, in particular, the 10% K value determined by the following method shows a small value of not more than a certain value. As a result, it is possible to achieve excellent softness which can sufficiently follow the deformation of the soft resin composition.

Specifically, the 10% K value of particles having a particle diameter of 10 ± 2 μm, 30 ± 2 μm or 50 ± 2 μm closest to the volume average particle diameter satisfies the following range.
10% K value of particles with a particle diameter of 10 ± 2 μm is 830 N / mm ² or less 10% K value of particles with a particle diameter of 30 ± 2 μm is 680 N / mm ² or less 10% K value of particles with particle diameter of 50 ± 2 μm is 320 N / Mm ² or less

  The above 10% K value is measured by applying a load toward the center of the test particle and measuring the load value when the compression displacement reaches 10% of the particle diameter, more specifically, by the method described in the examples described later. The compression modulus is determined by the following equation.

In the above equation, E is a compressive elastic modulus (N / mm ² ), F is a compressive load (N), S is a compressive displacement (mm), R is a radius of a particle (mm).

  When the volume average particle diameter is 20 μm, ie, an intermediate value between the particle diameter of 10 ± 2 μm and the particle diameter of 30 ± 2 μm, the 10% K value of particles of 10 ± 2 μm particle diameter and 30 ± 2 μm of particle diameter It is only necessary that one of the 10% K values of the particles satisfy the above range. When the volume average particle diameter is 40 μm, ie, an intermediate value between the particle diameter of 30 ± 2 μm and the particle diameter of 50 ± 2 μm, the 10% K value of particles having a particle diameter of 30 ± 2 μm and the particle diameter of 50 ± 2 μm It is only necessary that one of the 10% K values of the particles satisfy the above range.

10% K value of the particles having a particle size of 10 ± 2 [mu] m is in the as 830N / mm ² below, preferably 825N / mm ² or less, and more preferably not more than 820N / mm ^2. The lower limit of the 10% K value is not particularly limited, but is, for example, 15 N / mm ² or more, preferably 50 N / mm ² or more, and more preferably 100 N / mm ² or more.

10% K value of the particles having a particle size of 30 ± 2 [mu] m is in the as 680N / mm ² below, preferably 675N / mm ² or less, and more preferably not more than 670N / mm ^2. The lower limit of the 10% K value is not particularly limited, but is, for example, 10 N / mm ² or more, preferably 50 N / mm ² or more, and more preferably 100 N / mm ² or more.

10% K value of the particles having a particle size of 50 ± 2 [mu] m is in the as 320N / mm ² below, preferably 315N / mm ² or less, and more preferably not more than 310N / mm ^2. The lower limit of the 10% K value is not particularly limited, but is, for example, 5 N / mm ² or more, preferably 50 N / mm ² or more, and more preferably 100 N / mm ² or more.

  In the present invention, although the 10% K value of the particle diameter closest to the volume average particle diameter satisfies the above range, the volume average particle diameter of the particle diameters 10 ± 2 μm, 30 ± 2 μm and 50 ± 2 μm is further included. It is preferable that the 10% K value of the particle diameter other than the particle diameter closest to is also within the above range. For example, when particles having a volume average particle diameter of 35 μm and particles having a particle diameter of 10 ± 2 μm but without particles having a particle diameter of 50 ± 2 μm, not only the 10% K value of particles having a particle diameter of 30 ± 2 μm but It is preferable that the 10% K value of particles with a particle diameter of 10 ± 2 μm also satisfy the above range. When the particles have a volume average particle diameter of 35 μm and particles with a particle diameter of 10 ± 2 μm and particles with a particle diameter of 50 ± 2 μm, not only the 10% K value of particles with a particle diameter of 30 ± 2 μm but also the particle diameter 10 ± It is preferable that the 10% K value of particles of 2 μm and / or particles of 50 ± 2 μm in particle diameter also satisfy the above range.

  Although the core-shell particles of the present invention have high flexibility as described above, they have excellent powder handling properties. The handleability of the powder can be evaluated specifically by the proportion of core-shell particles passing through the sieve. The aggregation of the core-shell particles of the present invention is suppressed and the flowability is good, so that the proportion of the core-shell particles passing through the 1.18 mm mesh sieve can be 80% by mass or more. More preferably, the proportion of core-shell particles passing through a 1.18 mm mesh sieve is 100% by weight.

  Further, the core-shell particles of the present invention are superior in solvent resistance to particles of the soft material alone, although they have high softness as described above. That is, when the core-shell particles of the present invention are added to a solvent, it can be suppressed that the core-shell particles contain a solvent and swell. As a specific index of solvent resistance, the MEK (methyl ethyl ketone) swelling rate determined by the solvent resistance test according to the following procedure can be used.

  In the solvent resistance test, test tubes A and B with an inner diameter of 15 mm are prepared, 2.5 g of core-shell particles and 20 ml of 1% by mass emulsifier aqueous solution are put in the test tube A, and 2.5 g of core-shell particles are put in the test tube B Then, 20 ml of methyl ethyl ketone was added, test tubes A and B were dispersed with ultrasonic waves for 5 minutes each, and left for 12 hours, then the height of sedimented core-shell particles was measured, and the MEK swelling ratio was calculated according to the following formula (1) Do.

  MEK swelling ratio = (height of core-shell particles precipitated in methyl ethyl ketone (mm)) / (height of core-shell particles precipitated in aqueous emulsifier solution (mm)) (1)

  The core-shell particles of the present invention can make the above-mentioned MEK swelling ratio less than 3.0, preferably 2.8 or less, more preferably 2.5 or less. The lower limit of the MEK swelling ratio is not particularly limited and is preferably 1.0, but is usually about 1.1.

  The emulsifier used in the above-mentioned solvent resistance test is not particularly limited as long as the particles can be dispersed well. For example, polyoxyethylene alkyl ether sulfuric acid ester salt (for example, Hytenol (registered trademark, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Among the emulsifiers included in the shell pre-emulsion exemplified in the method for producing core-shell particles described later, an emulsifier having a polyoxyethylene chain may be mentioned as another preferable emulsifier which can be used) N- 08 ′ ′). Be

  Next, the components of the core portion and the shell portion constituting the core-shell particle of the present invention will be respectively described. In the present specification, the monomer unit means a structural unit derived from the monomer in the polymer. Moreover, in the present specification, “(meth) acryloyl group”, “(meth) acrylate” and “(meth) acrylic” are respectively “acryloyl group and / or methacryloyl group”, “acrylate and / or methacrylate”, “acrylic” And / or methacryl.

  The core part of the present invention comprises a copolymer having at least one monofunctional (meth) acrylic monomer (C1) unit and at least one crosslinkable (meth) acrylic monomer (C2) unit. preferable.

The monofunctional (meth) acrylic monomer (C1) is preferably a C _1-12 alkyl ester of (meth) acrylic acid. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) Acrylate, lauryl (meth) acrylate and the like can be mentioned, and one or two or more can be used, and it is preferable to use two or more in combination. As the monofunctional (meth) acrylic monomer unit (C1), the alkyl group is preferably a straight chain and a long chain, and the carbon number of the alkyl is more preferably 3 or more, and the carbon number of the alkyl Can be, for example, 10 or less, or 8 or less. Particularly preferably, n-butyl acrylate and n-butyl methacrylate are used in combination.

  The crosslinkable (meth) acrylic monomer (C2) means a compound having two or more (meth) acryloyl groups in one molecule. The two or more (meth) acryloyl groups are preferably bonded via a diol compound such as an alkylene glycol or a polyalkylene glycol; a triol compound; a tetraol compound; or a polyol compound such as a hexaol compound. In particular, the crosslinkable (meth) acrylic monomer (C2) is preferably a 2 to 6 functional crosslinkable (meth) acrylic monomer.

  Specifically as a bifunctional crosslinkable (meth) acrylic monomer, ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, Alkanediol di (meth) acrylates such as 1,9-nonanediol di (meth) acrylate; alkene glycol di (meth) acrylates such as 1,3-butylene glycol di (meth) acrylate; polyethylene glycol di (meth) acrylate ( The number of repeating ethylene glycol units is, for example, 2 to 150), and the like. Examples of trifunctional crosslinkable (meth) acrylic monomers include trimethylolpropane tri (meth) acrylate, and examples of tetrafunctional crosslinkable (meth) acrylic monomers include pentaerythritol tetra (meth) acrylate and the like. Examples of hexafunctional crosslinkable (meth) acrylic monomers include dipentaerythritol hexa (meth) acrylate and the like. The crosslinkable (meth) acrylic monomer (C2) may be used alone or in combination of two or more.

  The crosslinkable (meth) acrylic monomer (C2) is more preferably a 2 to 4 functional crosslinkable (meth) acrylic monomer, still more preferably a bifunctional crosslinkable (meth) acrylic monomer. Particularly preferred is polyethylene glycol di (meth) acrylate in which the number of repeating ethylene glycol units is 2 to 10, preferably 2 to 8.

  In the present invention, the glass transition temperature Tg of the polymer consisting only of the monofunctional (meth) acrylic monomer (C1) is preferably less than 0 ° C. By setting the glass transition temperature Tg to less than 0 ° C., the core portion becomes soft. The polymer consisting only of the monofunctional (meth) acrylic monomer (C1) extracts only monofunctional (meth) acrylic monomers from the monomers constituting the core portion, and the respective monofunctional (meth) acrylic monomers are extracted. It refers to a conceptual polymer obtained by (co) polymerizing only this compound while maintaining the ratio of. This conceptual polymer means a homopolymer consisting of only one type when using only one type as C1, and a copolymer consisting of two or more types of C1 when using two or more types as C1. means.

In the present invention, the glass transition temperature Tg means a value obtained by converting the glass transition temperature Tg _a of the absolute temperature obtained by the following formula (a) in degrees Celsius.

1 / Tg _a = Σ (W _i / T g _i ) (a)
In the above formula (a), Tg _a is the a monofunctional (meth) Glass transition temperature of the polymer composed only of the acrylic monomer (C1) (unit is an absolute temperature). _Wi is a mass ratio of each monofunctional (meth) acrylic monomer i in a polymer consisting only of the monofunctional (meth) acrylic monomer (C1). Tg _i is the glass transition temperature (unit: absolute temperature) of a homopolymer formed only from each monofunctional (meth) acrylic monomer i.

The above formula (a) is a formula called FOX formula, and for each monomer constituting the polymer, the glass transition temperature of the polymer based on the glass transition temperature Tg _i of the homopolymer of that monomer It is a formula for calculating Tg _a , and the details thereof are described in Bulletin of the American Physical Society, Series 2 (Vol. 1, No. 3, No. 3). It is described on page 123 (1956). In addition, the glass transition temperatures (Tg _i ) of homopolymers of various monomers for calculation with the FOX equation are described, for example, in Coatings and Paints (Coating Publishing Company, 10 (No. 358), 1982). Can be adopted.

  The glass transition temperature Tg of the polymer consisting of only the monofunctional (meth) acrylic monomer (C1), which is determined by converting the glass transition temperature determined by the FOX formula to degree Celsius, is preferably -5 ° C. or less. -10 ° C or less is more preferable, and -15 ° C or less is still more preferable. The lower limit of Tg is, for example, −50 ° C. or higher, and may be −45 ° C. or higher, or may be −40 ° C. or higher.

  The proportion of the monofunctional (meth) acrylic monomer (C1) unit in the copolymer of the core portion is, for example, 90% by mass or more, and by doing this, the core portion can be made more flexible. The proportion of the monofunctional (meth) acrylic monomer (C1) unit is preferably 92% by mass or more, more preferably 93% by mass or more, and most preferably 100% by mass.

  The proportion of the crosslinkable (meth) acrylic monomer (C2) unit in the copolymer of the core portion is preferably, for example, 10% by mass or less. By doing this, the core portion can be made more flexible. The proportion of the crosslinkable (meth) acrylic monomer (C2) unit is preferably 8% by mass or less, more preferably 7% by mass or less, and the lower limit is not particularly limited, and is, for example, 2% by mass or more.

  Next, the components of the shell portion of the present invention will be described. It is preferable that the shell part of this invention contains the copolymer which has at least 1 sort (s) of a monofunctional (meth) acrylic-type monomer (S1) unit, and at least 1 sort (s) of a crosslinkable monomer (S2) unit.

The monofunctional (meth) acrylic monomer (S1) is preferably a C _1-12 alkyl ester of (meth) acrylic acid. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) Acrylate, lauryl (meth) acrylate and the like can be mentioned, and one or more can be used. As the monofunctional (meth) acrylic monomer unit (S1), the above-mentioned alkyl group is preferably linear and long chain. The monofunctional (meth) acrylic monomer (S1) is preferably an ester of an alcohol having 3 or more carbon atoms and (meth) acrylic acid, and the carbon number is, for example, 10 or less, and further 8 or less. It can be an ester of alcohol and (meth) acrylic acid. More preferably, it is n-butyl methacrylate.

  The crosslinkable monomer (S2) may be any crosslinkable monomer, and specific examples thereof include vinyl crosslinkable monomers containing at least a vinyl group, and examples thereof include crosslinkable (meth) acrylic monomers, A crosslinkable styrenic monomer is mentioned. Preferred are crosslinkable (meth) acrylic monomers.

  The crosslinkable (meth) acrylic monomer means a compound having two or more (meth) acryloyl groups in one molecule. The two or more (meth) acryloyl groups are preferably bonded via a diol compound such as an alkylene glycol or a polyalkylene glycol; a triol compound; a tetraol compound; or a polyol compound such as a hexaol compound. In particular, the crosslinkable (meth) acrylic monomer is preferably a 2 to 6 functional crosslinkable (meth) acrylic monomer.

  Examples of the bifunctional crosslinkable (meth) acrylic monomer include esters of an aliphatic diol having two or more carbon atoms between two hydroxyl groups and (meth) acrylic acid. Specifically, ethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, etc. Alkanediol di (meth) acrylates; Alkene glycol di (meth) acrylates such as 1,3-butylene glycol di (meth) acrylates; eg polyethylene glycol di (meth) acrylates containing 2 to 150 ethylene glycol units; Be

  Examples of trifunctional crosslinkable (meth) acrylic monomers include trimethylolpropane tri (meth) acrylate, and examples of tetrafunctional crosslinkable (meth) acrylic monomers include pentaerythritol tetra (meth) acrylate and the like. Examples of hexafunctional crosslinkable (meth) acrylic monomers include dipentaerythritol hexa (meth) acrylate and the like. The crosslinkable (meth) acrylic monomer may be used alone or in combination of two or more.

  The crosslinkable (meth) acrylic monomer is more preferably a 2- to 4-functional crosslinkable (meth) acrylic monomer, and still more preferably a bifunctional crosslinkable (meth) acrylic monomer.

  In the bifunctional crosslinkable (meth) acrylic monomer, the alkyl group between two (meth) acryloyl groups is preferably linear and long chain, and the carbon number between two hydroxyl groups is 3 or more. More preferably, they are esters of aliphatic diols and (meth) acrylic acid. Further, it may be an ester of (meth) acrylic acid with an aliphatic diol having a carbon number of, for example, 10 or less, further 8 or less, further 6 or less between two hydroxyl groups. Or it is more preferable that it is polyethylene glycol di (meth) acrylate whose repeating number of an ethylene glycol unit is 2 or more. The number of repeating ethylene glycol units of the polyethylene glycol di (meth) acrylate is more preferably 3 or more. The upper limit of the number of repetitions of the ethylene glycol unit can be, for example, 10 or less, further 8 or less, and further 6 or less.

  Further, examples of the crosslinkable styrenic monomer include divinyl benzene, divinyl naphthalene, and derivatives thereof.

  The inclusion of the crosslinkable (meth) acrylic monomer unit as the crosslinkable monomer (S2) is preferable because the handleability of the powder can be sufficiently enhanced. The proportion of the crosslinkable (meth) acrylic monomer in the crosslinkable monomer (S2) is preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 100% by mass.

  The crosslinkable monomer (S2) unit in the shell part is 1 to 50 parts by mass with respect to a total of 100 parts by mass of the monofunctional (meth) acrylic monomer (S1) unit and the crosslinkable monomer (S2) unit Is preferred. By setting the crosslinkable monomer (S2) unit to 1 part by mass or more, the powder handleability and solvent resistance can be enhanced. The crosslinkable monomer (S2) unit is preferably 2 parts by mass or more. Moreover, the softness of a resin particle can be improved by setting a crosslinking | crosslinked monomer (S2) unit to 50 mass parts or less. The crosslinkable monomer (S2) unit is preferably 45 parts by mass or less.

  In the shell portion of the present invention, the glass transition temperature Tg of the polymer consisting of only the monofunctional (meth) acrylic monomer (S1) calculated based on the FOX formula is preferably 0 ° C. or more and less than 50 ° C. . That is, in the formula (a) used in the calculation of the glass transition temperature Tg in the core portion described above, the monofunctional (meth) acrylic monomer (C1) is replaced with the monofunctional (meth) acrylic monomer (S1) It is preferable that the glass transition temperature Tg of the polymer which consists only of the said monofunctional (meth) acrylic-type monomer (S1) calculated is 0 degreeC or more and less than 50 degreeC. By setting the glass transition temperature Tg to 0 ° C. or higher, good powder handling can be ensured. Further, by setting the glass transition temperature Tg to less than 50 ° C., the softness of the core portion can be sufficiently exhibited, and as a result, the softness of the resin particle can be sufficiently enhanced. The glass transition temperature Tg is more preferably 5 ° C. or more, further preferably 10 ° C. or more, and still more preferably 15 ° C. or more. The upper limit of the glass transition temperature Tg is more preferably 45 ° C. or less, still more preferably 40 ° C. or less, and still more preferably 35 ° C. or less.

  The polymer consisting only of the monofunctional (meth) acrylic monomer (S1) extracts only the monofunctional (meth) acrylic monomer from the monomers constituting the shell portion, and the respective monofunctional (meth) acrylic monomers are extracted. It refers to a conceptual polymer obtained by (co) polymerizing only this compound while maintaining the ratio of. This conceptual polymer means a homopolymer consisting of only one type when using only one type as S1, and a copolymer consisting of two or more types of S1 when using two or more types as S1. means.

Next, a method of producing core-shell particles according to the present invention, particularly core-shell particles in which the core part and the shell part satisfy the above-mentioned preferable components will be described. The production method is
(I) Monofunctional (meth) acrylic monomer (C1), crosslinkable (meth) acrylic monomer (C2), polymerization initiator, dispersion stabilizer (preferably water soluble polymer dispersion stabilizer), and aqueous solvent And (ii) a monofunctional (meth) acrylic monomer (S1) unit, a crosslinkable monomer (S2) unit, an emulsifier, and an aqueous solvent. And a step 2 of forming a shell polymerization portion on the surface of the core polymerization portion by bringing the emulsion liquid containing the following into contact with the reaction liquid containing the core polymerization portion obtained in the step 1;

Each step of the above manufacturing method will be described in more detail below.
(I) Monofunctional (meth) acrylic monomer (C1), crosslinkable (meth) acrylic monomer (C2), polymerization initiator, dispersion stabilizer (preferably water soluble polymer dispersion stabilizer), and aqueous solvent Forming a core polymer by reacting a suspension of the mixture containing

(I-1) Preparation of Suspension for Core First, in order to prepare a suspension for core, monofunctional (meth) acrylic monomer (C1), crosslinkable (meth) acrylic monomer (C2), polymerization The mixture containing the initiator, the dispersion stabilizer, and the aqueous solvent is placed in a container and stirred for a predetermined time to prepare a suspension.

  Water is used as a medium for providing a place for suspension polymerization, and the aqueous solvent may be water alone or a combination of water and a non-aqueous solvent, but water alone is preferable. . The amount of water is preferably 70 to 85 parts by mass in 100 parts by mass of the suspension.

  The above-mentioned dispersion stabilizer is used to stably advance the polymerization reaction, and is, for example, a water-soluble polymer-based dispersion stable such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone, cellulose, gelatin, sodium polyacrylate, sodium polymethacrylate and the like Agents; anionic surfactants such as sodium lauryl sulfate, polyoxyethylene alkylphenyl ether sulfate (for example, ammonium polyoxyethylene distyryl phenyl ether sulfate); cationic surfactants such as alkylamine salt and quaternary ammonium salt Surfactants; Amphoteric surfactants such as lauryldimethylamine oxide; Nonionic surfactants such as polyoxyethylene alkyl ether; Other alginates, zein, casein; Barium sulfate, calcium sulfate, carbonate Potassium, magnesium carbonate, calcium phosphate, talc, clay, diatomaceous earth, bentonite, titanium hydroxide, thorium hydroxide, or an inorganic dispersant such as metal oxide powder. As the dispersion stabilizer, a water-soluble polymer-based dispersion stabilizer is preferable, more preferably one or more of PVA, polyvinyl pyrrolidone, cellulose and gelatin, still more preferably one or more of PVA and polyvinyl pyrrolidone Preferably it is PVA. Further, from the viewpoint of securing higher affinity with the organic resin to be added, among the above, the water-soluble polymer-based dispersion stabilizer, various surfactants, other alginates, zein, casein, etc. It is preferred to use.

  The dispersion stabilizer is preferably, for example, 5 to 10 parts by mass in 100 parts by mass of the suspension for core.

  As a polymerization initiator, a radical polymerization initiator can be preferably used. The radical polymerization initiator is preferably a thermal polymerization initiator, and examples thereof include a peroxide type polymerization initiator and an azo compound type polymerization initiator. Examples of peroxide polymerization initiators include benzoyl peroxide, lauroyl peroxide, octanoyl peroxide, orthochlorobenzoyl peroxide, orthomethoxybenzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxydicarbonate, cumene hydroperoxide, cyclohexanone peroxide, t-butyl hydroperoxide And diisopropylbenzene hydroperoxide. Moreover, as an azo compound type polymerization initiator, 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,3-) Dimethylbutyronitrile), 2,2'-azobis- (2-methylbutyronitrile), 2,2'-azobis (2,3,3-trimethylbutyronitrile), 2,2'-azobis (2-) Isopropyl butyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-4-methoxy-2,4-dimethylvaleronitrile), 2- (carbamoylazo) isobutyronitrile, 4,4'-azobis (4-cyanovaleric acid), dimethyl-2,2'-azobisisobutyrate and the like can be mentioned.

  The polymerization initiator is preferably 0.1 to 1 part by mass in 100 parts by mass of the suspension for core.

  Stirring at the time of producing a suspension may be performed by stirring at about 200 to 400 rpm for about 1 to 3 hours using a paddle blade or the like, or high speed stirring at about 2000 to 4000 rpm for about 1 to 30 minutes. A well-known emulsification dispersion apparatus can be used for the above-mentioned high-speed stirring. As an emulsification dispersion apparatus, for example, Milder (manufactured by Ebara Corp.), T.K. K. High-speed shear turbine type dispersing machine such as Homomixer (manufactured by Primix); High pressure jet homogenizer such as piston type high pressure type homogenizing machine (manufactured by Gorin) or Microfluidizer (manufactured by Microfluids); Ultrasonic homogenizer (Nippon Seiki Co., Ltd.) For example, ultrasonic emulsifying and dispersing machines such as manufactured by Mfg. Co., Ltd .; medium stirring and dispersing machines such as Attrier (manufactured by Mitsui Mining Co., Ltd.); and forced gap passing type dispersing machines such as colloid mill (manufactured by Nippon Seiki Co., Ltd.).

(I-2) Polymerization of core monomer After preparation of the suspension for core, it is transferred to another container as necessary, and the temperature is raised under inert gas atmosphere while stirring, and the core monomer Polymerize the ingredients.

  As an inert gas, nitrogen gas, a rare gas, etc. can be used, and it is preferable to use nitrogen gas. The heating temperature is, for example, 40 to 100 ° C., preferably 50 to 90 ° C.

  The timing for mixing the suspension for core and the mixture containing a shell monomer described later is preferably performed at a stage at which the polymerization of the core monomer has sufficiently proceeded. The rate of polymerization of the core monomer can be estimated from the temperature change of the core suspension, and it is preferable to mix with the mixture containing the shell monomer immediately after the temperature of the core suspension exhibits a maximum value.

(Ii) An emulsion containing a monofunctional (meth) acrylic monomer (S1) unit, a crosslinkable monomer (S2) unit, an emulsifier, and an aqueous solvent, and a reaction liquid containing the core polymerization portion obtained in the above step 1 Forming a shell polymerization portion on the surface of the core polymerization portion by bringing

(Ii-1) Preparation of pre-emulsion containing monomer component for shell As a monomer component for shell, a monofunctional (meth) acrylic monomer (S1) unit, a crosslinkable monomer (S2) unit, an emulsifier, and an aqueous solvent are included, It is preferred to rapidly stir the initiator-free mixture and mix it as a pre-emulsion with the core suspension. By making the mixture containing the shell monomer into a pre-emulsion, the shell monomer component is uniformly dispersed in the core suspension, and the shell monomer component easily reaches the surface of the core particle.

  The suspension for the core has a polymerization initiator remaining, and the polymerization of the shell monomer proceeds by this polymerization initiator, so the shell pre-emulsion does not need to contain the polymerization initiator. Rather, when the polymerization initiator is contained, the shell monomer may be polymerized alone to form a shell portion. The pre-emulsion does not require a polymerization initiator, but may be contained within a range that does not inhibit the formation of the shell portion.

  The aqueous solvent may be water alone, or a combination of water and a non-aqueous solvent, but water alone is preferable. The amount of water is preferably 40 to 60 parts by mass in 100 parts by mass of the pre-emulsion.

  Emulsifiers are polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene sorbitan fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, oxyethylene-oxypropylene block copolymer Fatty acid salt, alkyl sulfate ester salt, alkyl benzene sulfonate, alkyl naphthalene sulfonate, alkane sulfonate, dialkyl sulfo succinate, alkyl phosphate ester salt, naphthalene sulfonic acid formalin condensate , Polyoxyethylene alkyl ether sulfate, polyoxyethylene phenyl ether sulfate, polyoxyethylene Anionic surfactants such as alkyl sulfates and the like, preferably an anionic surfactant (particularly polyoxyethylene phenyl ether sulfate) are used.

  The amount of the emulsifier is preferably 0.05 to 1.5 parts by mass (preferably 0.05 to 1 parts by mass) in 100 parts by mass of the pre-emulsion.

  The pre-emulsification of the mixture containing the shell monomer component, the aqueous solvent, and the emulsifier can be, for example, the same device as that which can be used for high-speed stirring of the above-mentioned suspension for shell.

  The amount of shell pre-emulsion can be, for example, 8 to 20 parts by mass with respect to 100 parts by mass of the core suspension.

(Ii-2) Polymerization of Monomer for Shell After mixing the suspension for core and the pre-emulsion for shell, the monomer for shell is maintained at 40 to 100 ° C. (preferably 50 to 90 ° C.) for 1 to 3 hours Can be polymerized. After completion of the polymerization of the core and the shell, filtration, centrifugation, drying and the like may be appropriately performed. Drying may be performed, for example, at 100 ° C. or less (preferably 30 to 50 ° C.) for about 5 to 20 hours.

  Hereinafter, the present invention will be more specifically described by way of examples. The present invention is not limited by the following examples, and it is of course possible to implement with appropriate modifications as long as it can conform to the above-mentioned and the following effects, and all of them can be technical of the present invention. It is included in the scope.

  The measuring methods of various physical properties carried out in the following examples are as follows.

(1) Volume average particle diameter and coefficient of variation (CV value) of resin particles
Add 20 parts of a 1% aqueous solution of polyoxyethylene alkyl ether sulfuric acid ester ammonium salt (Haitenol (registered trademark) N-08, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), which is an emulsifier, to 0.1 part of resin particles. A dispersion dispersed for 10 minutes by sound wave was used as a measurement sample. The particle diameter (μm) of 30,000 particles was measured by a particle size distribution measuring apparatus ("Coulter Multisizer III type" manufactured by Beckman Coulter, Inc.) to determine the volume average particle diameter. As for the variation coefficient of particle diameter, the standard deviation of particle diameter on a volume basis was determined together with the volume average particle diameter, and the variation coefficient (CV value) of particle diameter was calculated according to the following formula.
Particle diameter variation coefficient (%) = (Standard deviation of particle diameter based on volume / Volume average particle diameter) x 100

(2) Measurement of shell thickness In the production process of polymer particles described later, the average value of the particle diameter measured by sampling the polymer solution immediately before adding the emulsion liquid of the monomer component for shell and the weight finally obtained A value obtained by dividing the difference with the average value of the particle diameter measured for the united fine particles by 2 was taken as the shell thickness. Table 1 also shows the ratio of the shell thickness to the volume average particle size.

(3) 10% K value of resin particles "Soft surface" of one particle dispersed on a sample table (material: SKS flat plate) using a micro compression tester ("MCT-W500" manufactured by Shimadzu Corporation) In the “detection” mode, using a circular plate indenter (material: diamond) with a diameter of 50 μm, apply a load at a constant loading rate (2.2295 mN / s) toward the center of the particle, and the compression displacement becomes 10% of the particle diameter The compressive load value (mN) at the time of becoming and the displacement (.mu.m) at that time were measured. The diameter of the resin particles was measured using a caliper size calculation tool attached to the above MCT-W500. The resin particles to be measured are as shown in the following “(4) Evaluation of flexibility of resin particles”. Then, the obtained compressive load value (mN) is converted to a compressive load (N), the displacement amount (μm) obtained at that time is converted to a compressive displacement (mm), and the average particle diameter of resin particles (μm) The radius (mm) of the particles was calculated from the above, and calculated using the following formula. The above measurement was performed under a constant temperature atmosphere of 25 ° C.

In the above formula, E: compressive modulus (N / mm ² ), F: compressive load (N), S: compressive displacement (mm), R: radius of particle (mm).

(4) Evaluation of softness of resin particles The softness is evaluated according to the following procedure.
[1] As shown in the above (1), the volume average particle diameter is measured by a particle size distribution measuring apparatus.
[2] Select the particle diameter closest to the volume average particle diameter among the particle diameters 10 ± 2 μm, 30 ± 2 μm, and 50 ± 2 μm.
[3] Measure the particle diameter of 10 resin particles with the selected particle diameter of 10 ± 2 μm, 30 ± 2 μm, or 50 ± 2 μm with MCT-W500 using the attached caliper calculation tool.
[4] The 10% K value of each of the 10 resin particles measured above is calculated, and the average value thereof is determined.
For example, when the volume average particle diameter is 35 μm, 10 resin particles having a particle diameter of 30 ± 2 μm measured by using the above tool are collected, and the 10% K value of these resin particles is measured. The mean value is taken as the 10% K value of particles of particle diameter 30 ± 2 μm. And softness is evaluated by the following index. In Table 1, in any of the examples, in addition to the 10% K value of the particle diameter 30 ± 2 μm closest to the volume average particle diameter, the 10% K value of the particles 10 ± 2 μm particle diameter and the particle diameter 50 ± 2 μm The 10% K value of the particles of is also shown.
[Flexibility Index]
When the particle diameter is 10 ± 2 μm 830 N / mm ² or less is “○”, 830 N / mm ² is “×”
When the particle size is 30 ± 2 μm ○ 680 N / mm ² or less is "○", 680 N / mm ^{2 or} more is "×"
When the particle size is 50 ± 2 μm 320N / mm ² or less is "○", 320N / mm ^{2 or} more is "×"

(5) Evaluation of handleability of powder (resin particles) After placing 100 g of polymer particles on a 1.18 mm mesh sieve and shaking for 1 minute, measure the mass of the polymer particles passing through the sieve, The pass rate was determined by the following equation.

Pass rate (%) = (weight of polymer fine particles passing through sieve (g) / 100 (g)) × 100

  Those having a pass ratio of 80 to 100% by mass were evaluated as “o”, and those having less than 80 mass% were evaluated as “x”.

(6) Evaluation of solvent resistance of resin particles Test tubes A and B with an inner diameter of 15 mm are prepared, and 2.5 g of resin particles and a polyoxyethylene alkyl ether sulfate ester ammonium salt (Daiichi Kogyo Seiyaku Co., Ltd. 20 ml of a 1% by mass aqueous solution of “Hitenol (registered trademark) N-08” manufactured by Co., Ltd., and 2.5 g of resin particles and 20 ml of methyl ethyl ketone in test tube B, The mixture was ultrasonically dispersed for a minute and left for 12 hours. The height of the precipitated resin particles was measured, and the MEK swelling ratio was calculated according to the following formula (1). In the following formula (1), core-shell particles are expressed as resin particles.
MEK swelling ratio = (height of resin particles precipitated in methyl ethyl ketone (mm)) / (height of resin particles precipitated in aqueous emulsifier solution (mm)) (1)

  Those with a MEK swelling ratio of less than 3.0 were evaluated as "o", and those with 3.0 or more as "x".

(Production Example 1)
666.7 parts (hereinafter "parts" is "parts by mass") of a 10% aqueous solution of polyvinyl alcohol ("Poval PVA-205" manufactured by Kuraray Co., Ltd.) in a four-necked flask equipped with a cooling pipe, thermometer and dropping port Mean) was kept at 25 ° C. Under stirring at 235 rpm, 47.5 parts of n-butyl acrylate (47.5% by mass of all the core monomers) as monomer components for the core and 47.5 parts of n-butyl methacrylate (for all cores) from the dropping port 47.5% by mass in monomers), 5.0 parts of triethylene glycol dimethacrylate (5% by mass in monomers for all cores), 2,2'-azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd.) A suspension was prepared by adding a solution in which 3.0 parts of company "V-65" was dissolved and holding for 2 hours. The suspension was subjected to radical polymerization of the core monomer component by raising the temperature to 65 ° C. in a nitrogen atmosphere under continuous stirring. The glass transition temperature of the homopolymer of n-butyl acrylate is 218.2 K, and the glass transition temperature of the homopolymer of n-butyl methacrylate is 293.2 K.

  Then, 1.3 parts of a 20% aqueous solution of polyoxyethylene styrenated phenyl ether sulfate ammonium salt ("Hiteen (registered trademark) NF-08" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as an emulsifier in another flask, In a solution dissolved in 50.0 parts of ion-exchanged water, 47.5 parts of n-butyl methacrylate (47.5 parts by mass with respect to a total of 100 parts by mass of the core monomer) as a shell monomer component, and triethylene 2.5 parts by weight of glycol dimethacrylate (2.5 parts by weight with respect to a total of 100 parts by weight of the core monomer) was added and emulsified and dispersed to prepare an emulsion of shell monomer components.

  Immediately after the polymerization of the core monomer component started and the temperature inside the flask reached the peak temperature and showed the maximum value, the emulsion of the shell monomer component was added. Radical polymerization of the shell monomer component was carried out by holding at 65 ° C. for 2 hours after the addition. The emulsion after radical polymerization was subjected to solid-liquid separation, and vacuum dried at 40 ° C. for 12 hours to obtain polymer fine particles (1). Each physical property of the obtained resin particle was as showing in Table 1.

(Production Examples 2 to 5)
Fine polymer particles (2) to (5) were obtained in the same manner as in Production Example 1 except that the types and amounts of the monomers were as shown in Table 1. Physical properties of the obtained polymer fine particles are as shown in Table 1.

(Production Example 6)
In a four-necked flask equipped with a cooling pipe, a thermometer and a dropping port, 666.7 parts of a 10% aqueous solution of polyvinyl alcohol ("Poval PVA-205" manufactured by Kuraray Co., Ltd.) was charged and maintained at 25 ° C. 60.0 parts of methyl methacrylate as monomer components, 40.0 parts of ethylene glycol dimethacrylate and 2,2'-azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd.) from the dropping port while stirring at 200 rpm A solution obtained by dissolving 2.0 parts of "V-65" (manufactured by Kogyo Co., Ltd.) was added, and a suspension was prepared by holding for 2 hours. The suspension was subjected to radical polymerization of the monomer component by raising the temperature to 65 ° C. in a nitrogen atmosphere under continuous stirring. The emulsion after radical polymerization was subjected to solid-liquid separation, and vacuum dried at 40 ° C. for 12 hours to obtain polymer fine particles (6). Each physical property of the obtained resin particle was as showing in Table 1.

(Production Example 7)
Fine polymer particles (7) were obtained in the same manner as in Production Example 6 except that the types and amounts of the monomers were as shown in Table 1. Physical properties of the obtained polymer fine particles are as shown in Table 1.

  In Table 1, nBMA is n-butyl methacrylate, nBA is n-butyl acrylate, 3 EG is triethylene glycol dimethacrylate, MMA is methyl methacrylate, EGDMA is ethylene glycol dimethacrylate, DVB is divinyl benzene, St is Represents styrene. The degree of shell crosslinking is a value indicating the mass ratio of the content of the crosslinkable monomer to the content of all the monomers in the shell as a percentage.

  From Table 1, it is understood that Examples 1 and 2 satisfying the requirements of the present invention are all excellent in softness and excellent in powder handling properties, and also low in MEK swelling rate and excellent in solvent resistance.

  On the other hand, in Comparative Examples 1 to 3, since the 10% K value of the particles having a particle diameter of 30 ± 2 μm closest to the volume average particle diameter is high, the softness is inferior. Moreover, when Example 1 and Comparative Example 2 are compared, in order to obtain resin particles excellent in powder handling properties as well as excellent softness, the shell portion is a monofunctional (meth) acrylic monomer (S1) unit. It is preferable to use a copolymer having at least one of at least one of the following and at least one of the crosslinkable monomer (S2) unit, and more preferably, the crosslinkable monomer (S2) unit is a crosslinkable (meth) acrylic monomer unit It turns out that it is preferable.

  Comparative Example 4 was inferior in flexibility because it had only a hard core portion and no shell portion. In addition, Comparative Example 5 was inferior in the handleability and the solvent resistance of the powder because it had only a soft core portion and no shell portion.

  The core-shell particles of the present invention are useful as additives (modifiers) for enhancing the functional properties such as mechanical properties and optical properties of rubbers, films, paints, inks, adhesives and the like. The core-shell particles of the present invention are specifically, for example, ethylene-propylene-diene rubber, ethylene-propylene rubber, isoprene rubber, butyl rubber, styrene-butadiene rubber, polybutadiene rubber, NBR rubber, natural rubber, fluororubber chloroprene rubber, polyethylene resin, Polypropylene resin, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, styrene-butadiene resin, polyacetal resin, polystyrene resin, vinyl chloride-vinyl acetate resin, acrylic resin, polymethyl methacrylate resin, polyester resin, polyamide resin, polyimide resin, Polyurethane resin, epoxy resin, phenol resin, amino resin, polycarbonate resin, polyfluoroolefin resin, cellulose resin, alkyd resin, It was added to lamin resins, useful as additives for improving the properties (modifier).

Claims (11)

A core-shell particle comprising a core portion and a shell portion provided on the surface thereof,
The volume average particle diameter is 3 μm or more and 150 μm or less,
The 10% K value of particles having a particle diameter of 10 ± 2 μm, 30 ± 2 μm or 50 ± 2 μm, which has a coefficient of variation of particle diameter of 20% or more and is closest to the volume average particle diameter, has the following range Core-shell particles characterized by filling.
10% K value of particles with a particle diameter of 10 ± 2 μm is 830 N / mm ² or less 10% K value of particles with a particle diameter of 30 ± 2 μm is 680 N / mm ² or less 10% K value of particles with particle diameter of 50 ± 2 μm is 320 N / Mm ² or less The core portion includes a copolymer having at least one of monofunctional (meth) acrylic monomer (C1) units and at least one of crosslinkable (meth) acrylic monomer (C2) units, and has a FOX formula The glass transition temperature Tg of the polymer consisting of only the monofunctional (meth) acrylic monomer (C1) calculated based on the basis is less than 0 ° C.,
The said shell part contains the copolymer which has at least 1 sort (s) of a monofunctional (meth) acrylic-type monomer (S1) unit, and at least 1 sort (s) of a crosslinkable monomer (S2) unit, It calculates based on FOX Formula The core-shell particle according to claim 1, wherein the glass transition temperature Tg of the polymer comprising only the monofunctional (meth) acrylic monomer (S1) is 0 ° C or more and less than 50 ° C. A core-shell particle comprising a core portion and a shell portion provided on the surface thereof,
The core portion includes a copolymer having at least one of monofunctional (meth) acrylic monomer (C1) units and at least one of crosslinkable (meth) acrylic monomer (C2) units, and has a FOX formula The glass transition temperature Tg of the polymer consisting of only the monofunctional (meth) acrylic monomer (C1) calculated based on the basis is less than 0 ° C.,
The said shell part contains the copolymer which has at least 1 sort (s) of a monofunctional (meth) acrylic-type monomer (S1) unit, and at least 1 sort (s) of a crosslinkable monomer (S2) unit, It calculates based on FOX Formula A core-shell particle characterized in that the glass transition temperature Tg of the polymer comprising only the monofunctional (meth) acrylic monomer (S1) is 0 ° C. or more and less than 50 ° C.   The core-shell particle according to claim 2 or 3, wherein the monofunctional (meth) acrylic monomer (S1) in the shell part is an ester of an alcohol having 3 or more carbon atoms and (meth) acrylic acid.   The core-shell particle according to any one of claims 2 to 4, wherein a crosslinkable (meth) acrylic monomer unit is contained as the crosslinkable monomer (S2) unit of the shell part.   The core-shell particle according to claim 5, wherein the crosslinkable (meth) acrylic monomer in the shell portion is polyethylene glycol di (meth) acrylate having a repeating number of ethylene glycol units of 2 or more.   The crosslinkable monomer (S2) unit in the shell portion is 1 to 50 parts by mass with respect to 100 parts by mass in total of the monofunctional (meth) acrylic monomer (S1) unit and the crosslinkable monomer (S2) unit. The core-shell particle according to any one of Items 2 to 6.   The core-shell particle according to any one of claims 1 to 7, wherein a proportion of particles passing through a sieve having an opening of 1.18 mm is 80% by mass or more. The core-shell particle according to any one of claims 1 to 8, which has a MEK swelling ratio of less than 3.0 as calculated by the following solvent resistance test.
[Solvent resistance test]
Test tubes A and B with an inner diameter of 15 mm are prepared, 2.5 g of core-shell particles and 20 ml of a 1% by mass emulsifier aqueous solution are put in the test tube A, and 2.5 g of core-shell particles and 20 ml of methyl ethyl ketone are put in the test tube B The test tubes A and B are each dispersed with ultrasonic waves for 5 minutes and left for 12 hours, and then the height of the sedimented core-shell particles is measured, and the MEK swelling ratio is calculated according to the following formula (1).
MEK swelling ratio = (height of core-shell particles precipitated in methyl ethyl ketone (mm)) / (height of core-shell particles precipitated in aqueous emulsifier solution (mm)) (1)   The core-shell particle according to any one of claims 1 to 9, wherein the ratio of the thickness of the shell portion to the volume average particle diameter is 0.03 or more and 0.12 or less. A suspension of a mixture containing a monofunctional (meth) acrylic monomer (C1), a crosslinkable (meth) acrylic monomer (C2), a polymerization initiator, a water-soluble polymer dispersion stabilizer, and an aqueous solvent is reacted A step 1 of forming a core polymerization portion, and an emulsion containing a monofunctional (meth) acrylic monomer (S1) unit, a crosslinkable monomer (S2) unit, an emulsifier, and an aqueous solvent; Step 2 of forming a shell polymerization portion on the surface of the core polymerization portion by bringing the reaction solution containing the core polymerization portion into contact with each other
The method for producing core-shell particles according to any one of claims 2 to 10, comprising: