Nucleating agent composition, resin composition, molded article thereof, and method for manufacturing resin composition

A resin composition, comprising a polyolefin-based resin and at least one type of a nucleating agent for a polyolefin-based resin,

• wherein a β crystal fraction ranges from 0.2% to 71% as calculated by the following method,
• <Method for calculating β crystal fraction>
• (1) After the resin composition is dried at 80° C. for 8 hours, 10 mg of a sample is sampled from the dried pellets, and then the sample is introduced into a differential scanning calorimeter,
• (2) Using the differential scanning calorimeter, differential scanning calorimetry is performed according to a temperature program of heating the sample from 25° C. to 230° C. at a rate of 50° C./min, maintaining the sample at 230° C. for 20 minutes, cooling the sample to 50° C. at a rate of 100° C./min, maintaining the sample at 50° C. for 20 minutes, and then increasing the temperature to 230° C. at a rate of 30° C./min, thereby obtaining a DSC curve, Q=f(θ), with the horizontal axis being temperature θ (° C.) and the vertical axis being heat flow rate Q(mW). Here, regarding the vertical axis, the endothermic direction is assumed to be positive,
• (3) In a portion of the DSC curve, which corresponds to the second temperature rising process in the temperature program, a baseline g(6)=(f(200)−f(110))/90×(θ−110)+f(110) is subtracted from f(θ) to obtain a baseline-corrected DSC curve, Q′=h(θ)=f(θ)−g(θ),
• (4) The area of a region surrounded by the portion of 110≤θ≤200 of the curve Q′=h(θ) and line segment AB connecting point A (110, 0) and point B (200, 0) is determined to be St. Here, St is represented by the following formula,
• St=∫110220h(θ)dθ
• (5) Two maximum points in the range of 110≤θ≤200 on the curve Q′=h(θ) are determined to be R(θβ,h(θβ)) and S(θα,h(θα)) (where θβ<θα), and the minimum point in the range of θβ<θ<θα on the curve Q′=h(θ) is determined to be C(θγ,h(θγ). Then a tangent is drawn to pass through point C and come into contact with the curve Q′=h(θ) in the range of 110<θ<θβ, determining the contact point as point D (θδ,h(θδ). Then, the area of a region surrounded by the portion of θδ≤θ≤θγ of the curve Q′=h(θ) and line segment DC connecting point D and point C is determined to be Sβ,
• Here, Sβ is represented by the following formula,
• S
• β
• =
• ∫
• θ
• δ
• θ
• γ
• j
• ⁡
• (
• θ
• )
• ⁢
• d
• ⁢
• θ
• wherein j(θ)=h(θ)−i(θ) and i(θ)=(h(θγ)−h(θδ))/(θγ−θδ)×(θ−θγ)+h(θγ),
• (6) A β crystal fraction (%) is calculated from St and Sβ above by the following formula,
• β
• ⁢
• crystal
• ⁢
• fraction
• =
• S
• β
• /
• S
• t
• ×
• 1
• ⁢
• 0
• ⁢
• 0
• ⁢
• (
• %
• )

A method for manufacturing a resin composition, comprising a blending step of blending at least one type of a nucleating agent for a polyolefin-based resin in a polyolefin-based resin, in such a manner that a β crystal fraction ranges from 0.2% to 71% as calculated by the following method,

• <Method for calculating β crystal fraction>
• (1) After the resin composition is dried at 80° C. for 8 hours, 10 mg of a sample is sampled from the dried pellets, and then the sample is introduced into a differential scanning calorimeter,
• (2) Using the differential scanning calorimeter, differential scanning calorimetry is performed according to a temperature program of heating the sample from 25° C. to 230° C. at a rate of 50° C./min, maintaining the sample at 230° C. for 20 minutes, cooling the sample to 50° C. at a rate of 100° C./min, maintaining the sample at 50° C. for 20 minutes, and then increasing the temperature to 230° C. at a rate of 30° C./min, thereby obtaining a DSC curve, Q=f(θ), with the horizontal axis being temperature θ(° C.) and the vertical axis being heat flow rate of Q(mW). Here, regarding the vertical axis, the endothermic direction is assumed to be positive,
• (3) In a portion of the DSC curve, which corresponds to the second temperature rising process in the temperature program, a baseline g(θ)=(f(200)−f(110))/90×(θ−110)+f(110) is subtracted from f(θ) to obtain a baseline-corrected DSC curve Q′=h(θ)=f(θ)−g(θ),
• (4) The area of a region surrounded by the portion of 110≤θ≤200 of the curve Q′=h(θ) and line segment AB connecting point A (110, 0) and point B (200, 0) is determined to be St. Here, St is represented by the following formula,
• St=∫110220h(θ)dθ
• (5) Two maximum points in the range of 110≤θ≤200 on the curve Q′=h(θ) are determined to be R(θβ,h(θβ)) and S(θα,h(θα)) (where θβ<θα), and the minimum point in the range of θβ<θ<θα on the curve Q′=h(θ) is determined to be C(θγ,h(θγ). Then a tangent is drawn to pass through point C and come into contact with the curve Q′=h(θ) in the range of 110<θ<θβ, determining the contact point as point D (θδ,h(θδ). Then, the area of a region surrounded by the portion of θδ≤θ≤θγ of the curve Q′=h(θ) and line segment DC connecting point D and point C is determined to be Sβ.
• Here, Sβ is represented by the following formula,
• S
• β
• =
• ∫
• θ
• δ
• θ
• γ
• j
• ⁡
• (
• θ
• )
• ⁢
• d
• ⁢
• θ
• wherein j(θ)=h(θ)−i(θ) and i(θ)=(hθγ)−h(θδ))/(θγ−θδ)×(θ−θγ)+h(θγ),
• (6) A β crystal fraction (%) is calculated from St and Sβ above by the following formula,
• β
• ⁢
• crystal
• ⁢
• fraction
• =
• S
• β
• /
• S
• t
• ×
• 1
• ⁢
• 0
• ⁢
• 0
• ⁢
• (
• %
• )