Method for manufacturing elastic cylindrical body, method for manufacturing elastic roll, elastic cylinerical body and elastic roll

A method of manufacturing an elastic cylindrical body by casting a liquid mixture containing a liquid polymeric material and a filler into a mold (11) for centrifugal molding and performing centrifugal molding thereby preparing a cylindrical body having said filler dispersed in the polymeric material, comprising steps of:

• performing said centrifugal molding under conditions satisfying the following equations [7] and [8], and;
• removing a skin layer, when a high-density packed bed is formed on said cylindrical body as said skin layer:
• X≧T [7]Y≦T/100 [8]
• where
• 7 X = 2.3 × 10 - 7 ⁢ ∫ t 0 t g ⁢ ⁢ p ⁢ 0.2 2 ⁢ ρ m ⁢ R ⁢ ⁢ N t 2 η t ⁢ ⁢ ⅆ t [ 9 ] Y = 6.1 × 10 - 7 ⁢ ∫ t 0 t g ⁢ ⁢ p ⁢ D P 2 ⁡ ( ρ P - ρ ) ⁢ r ⁢ ⁢ N t 2 μ t ⁢ ⁢ ⅆ t [ 10 ]
• (in the above equations, T (mm) represents the thickness of said cylindrical body,
• t0=0,
• tgp (s) represents the time required for gelation of said liquid mixture,
• ρm represents the specific gravity of said liquid mixture,
• R (mm) represents the inner radius of said mold (11),
• Nt (rpm) represents the rotational frequency of said mold (11) at a time t in said centrifugal molding step,
• ηt (Pa·s) represents the viscosity of said liquid mixture at the time t,
• Dp (mm) represents the 80 cumulative weight % particle diameter of said filler,
• ρp represents the specific gravity of said filler,
• ρ represents the specific gravity of said liquid polymeric material,
• r (mm) represents the inner radius of said cylindrical body, and
• μt (Pa·s) represents the viscosity of said liquid polymeric material at the time t upon heating under the same condition as said centrifugal molding respectively).

A method of manufacturing an elastic cylindrical body, comprising:

• a centrifugal molding step of casting a liquid mixture containing a liquid polymeric material and a filler into a mold (11) for centrifugal molding and performing centrifugal molding thereby preparing a cylindrical body including a homogeneous dispersion layer (2) having said filler homogeneously dispersed in the polymeric material and a high-density packed bed (1), formed on the outer peripheral surface side or on the inner peripheral surface side of said homogeneous dispersion layer (2), containing said polymeric material more densely filled with said filler;
• a removing step of removing said high-density packed bed (1) and exposing said homogeneous dispersion layer (2) on the surface;
• and
• a step of putting said cylindrical body on the outer side of a core (3) before said removing step or after said removing step for integrating said cylindrical body and said core (3) with each other.

A method of manufacturing an elastic roll including:

• a centrifugal molding step of casting a liquid mixture containing a liquid polymeric material and a filler into a mold (11) for centrifugal molding and performing centrifugal molding thereby preparing a cylindrical body having said filler dispersed in the polymeric material,
• a step of removing a skin layer, when a high-density packed bed is formed on said cylindrical body as said skin layer, and
• a step of putting said cylindrical body on the outer side of a core (3) for integrating said cylindrical body and said core (3) with each other,
• performing said centrifugal molding under conditions satisfying the following equations [11] and [12]:
• X≧T [11]Y≦T/100 [12]
• where
• 8 X = 2.3 × 10 - 7 ⁢ ∫ t 0 t g ⁢ ⁢ p ⁢ 0.2 2 ⁢ ρ m ⁢ R ⁢ ⁢ N t 2 η t ⁢ ⁢ ⅆ t [ 13 ] Y = 6.1 × 10 - 7 ⁢ ∫ t 0 t g ⁢ ⁢ p ⁢ D P 2 ⁡ ( ρ P - ρ ) ⁢ r ⁢ ⁢ N t 2 μ t ⁢ ⁢ ⅆ t [ 14 ]
• (in the above equations, T (mm) represents the thickness of said cylindrical body,
• t0=0,
• tgp (s) represents the time required for gelation of said liquid mixture,
• ρm represents the specific gravity of said liquid mixture,
• R (mm) represents the inner radius of said mold (11),
• Nt (rpm) represents the rotational frequency of said mold (11) at a time t in said centrifugal molding step,
• ηt (Pa·s) represents the viscosity of said liquid mixture at the time t,
• Dp (mm) represents the 80 cumulative weight % particle diameter of said filler,
• ρp represents the specific gravity of said filler,
• ρ represents the specific gravity of said liquid polymeric material,
• r (mm) represents the inner radius of said cylindrical body, and
• μt (Pa·s) represents the viscosity of said liquid polymeric material at the time t upon heating under the same condition as said centrifugal molding respectively).

An elastic cylindrical body containing a polymeric material and a filler,

• obtained by centrifugal molding, wherein
• the difference between the hardness of the outer surface and the hardness of the inner surface is within 2 degrees (JIS D),
• the difference in hardness per millimeter in the thickness direction is within 1 degree (JIS D), and
• the 80 cumulative weight % particle diameter of said filler [Dp] ranges from 0.01 μm to 20 μm.

An elastic cylindrical body containing a polymeric material and a filler,

• obtained by centrifugal molding, wherein
• the difference between the ash content on an outer surface portion and the ash content on an inner surface portion is within 20%,
• the difference in ash content per millimeter in the thickness direction is within 10% and
• the 80 cumulative weight % particle diameter of said filler [Dp] ranges from 0.01 μm to 20 μm

An elastic roll including a core (3) and an elastic cylindrical body located on the outer side of said core (3) and integrated with said core (3), wherein

• said elastic cylindrical body contains a polymeric material and a filler, and
• is obtained by centrifugal molding,
• the difference between the hardness of the outer surface and the hardness of the inner surface is within 2 degrees (JIS D),
• the difference in hardness per millimeter in the thickness direction is within 1 degree (JIS D) and
• the 80 cumulative weight % particle diameter of said filler [Dp] ranges from 0.01 μm to 20 μm.

An elastic roll including a core (3) and an elastic cylindrical body located on the outer side of said core (3) and integrated with said core (3), wherein

• said elastic cylindrical body contains a polymeric material and a filler, and
• is obtained by centrifugal molding,
• the difference between the ash content on an outer surface portion and the ash content on an inner surface portion is within 20%,
• the difference in ash content per millimeter in the thickness direction is within 10% and
• the 80 cumulative weight % particle diameter of said filler [Dp] ranges from 0.01 μm to 20 μm.