Polyester-based resin foam and method for producing resin composite

Abstract

A resin composite having excellent strength is easily produced by using a resin foam having a specific surface roughness (Ra) as the core material of the resin composite.

Claims

1. A method for producing a resin composite, comprising: performing a laminating step of using a fiber-reinforced resin sheet and a core material including a resin foam, and integrally laminating said core material and said fiber-reinforced resin sheet to form the resin composite, wherein said fiber-reinforced resin sheet comprises a substrate sheet including a fiber woven fabric and a resin impregnated in said substrate sheet, said core material is a polyester-based resin foam having a surface roughness (Ra) of 2.41 m or less, and in the laminating step, said fiber-reinforced resin sheet is laminated on a surface of said polyester-based resin foam, the surface having said surface roughness (Ra), wherein said polyester-based resin foam is crosslinked by a crosslinking agent, wherein the crosslinking is performed using a ratio of 0.01 parts by mass or more and 5 parts by mass or less of the crosslinking agent based on 100 parts by mass of the polyester-based resin foam performing a sheet preparing step of extrusion foaming a polyester-based resin composition to prepare a polyester-based resin expanded sheet to be used as said core material, and performing a sheet smoothing step of smoothing a surface of said polyester-based resin expanded sheet obtained in the sheet preparing step, in the sheet preparing step, said polyester-based resin expanded sheet having a surface roughness (Ra) exceeding 2.5 m is prepared, in the sheet smoothing step, a surface of said polyester-based resin expanded sheet is smoothed so that said surface roughness (Ra) becomes 2.41 m or less, and in the laminating step, said fiber-reinforced resin sheet is laminated on a surface of said polyester-based resin expanded sheet, said surface having been smoothed in the sheet smoothing step.

Description

EXAMPLES

(1) The present invention will be further explained in detail based on Examples below, but the present invention is not limited by them.

Examples 1 and 2

(2) A thermoplastic polyester-based resin composition comprising 100 parts by mass of a polyethylene terephthalate resin (PET, product name SA135, manufactured by Mitsui Chemicals, Inc., glass transition temperature Tg: 79 C., melting point: 247.1 C., IV value: 0.86), 0.72 parts by mass of talc, and 0.2 part of pyromellitic anhydride was supplied to a single screw extruder having a pore diameter of 65 mm and the L/D ratio of 35, and melt-kneaded at 290 C.

(3) Then, butane comprising 36% by mass of isobutane and 65% by mass of normal butane was pressed into a middle part of the single screw extruder so that the butane became 1.0 parts by mass based on 100 parts by mass of polyethylene terephthalate.

(4) Then, the butane was uniformly dispersed in the thermoplastic polyester-based resin composition, in the single screw extruder.

(5) Thereafter, at the front end of the single screw extruder, after the polyester-based resin composition in the melt state was cooled to 220 C., and then it was extrusion foamed in a cylindrical shape through a circular die mounted at the front end of the single screw extruder to produce a cylindrical body.

(6) A diameter of this cylindrical body was gradually expanded, and the cylindrical body was supplied to a cooling mandrel to cool the body so that a surface temperature thereof became 25 C.

(7) The cylindrical body after cooling was cut over in internal and external circumferential planes (in the direction of the thickness).

(8) Cutting was continuously carried out in the direction of the extruding, and the cylindrical body after cutting was unfolded, thereby obtaining a band-like polyethylene terephthalate expanded sheet.

(9) The obtained polyethylene terephthalate expanded sheet had the thickness of 3.2 mm and the weight per unit area of 900 g/m.sup.2.

(10) In addition, hereinafter, the surface contacted with the cooling mandrel is called a front surface of the expanded sheet, and the surface on the opposite side is called as a rear surface.

(11) The expanded sheet was placed under the environment at a room temperature of 25 C. immediately after production, and was cured over 48 hours under the same environment.

(12) For the expanded sheet after curing, the following sheet smoothing step was carried out.

(13) A planar square-shaped sheet piece having one side of 640 mm was excised from the expanded sheet.

(14) The excised sheet piece was mounted in a pressing machine provided with a 3.0 mm spacer, and was pressed at a temperature of 140 C. and a pressure of 0.5 MPa for 3 minutes.

(15) Thereafter, the pressed piece was cooled to 30 C. while retaining a pressure, to obtain a surface-smoothed expanded sheet (sheet piece) having the thickness and the weight per unit area described in Table 1.

Examples 3 and 4

(16) In the same manner as in Examples 1 and 2 except that, at a middle part of the single screw extruder, butane comprising 35% by mass of isobutane and 65% by mass of normal butane was pressed into a polyester-based resin composition in the melt state so that the butane became 0.5 parts by mass based on 100 parts by mass of polyethylene terephthalate, a polyethylene terephthalate expanded sheet having the thickness of 2.0 mm and the weight per unit area of 600 g/m.sup.2 was produced, and an excised sheet piece was mounted and pressed in a pressing machine provided with a 1.5 min spacer, thereby obtaining a surface-smoothed expanded sheet.

Examples 5 and 6

(17) In the same manner as in Examples 1 and 2 except that, at a middle part of the single screw extruder, butane comprising 35% by in mass of isobutane and 65% by mass of normal butane was pressed into a polyester-based resin composition in the melt state so that the butane became 0.3 parts by mass based on 100 parts by mass of polyethylene terephthalate, a polyethylene terephthalate expanded sheet having the thickness of 1.7 mm and the weight per unit area of 500 g/m.sup.2 was produced, and an excised sheet piece was mounted and pressed in a pressing machine provided with a 1.5 mm spacer, thereby obtaining a surface-smoothed expanded sheet.

Comparative Examples 1 and 2

(18) In the same manner as in Examples 1 and 2, an expanded sheet was produced, but the sheet smoothing step was not performed.

Comparative Example 3 and 4

(19) In the same manner as in Examples 5 and 6, an expanded sheet was produced, but the sheet smoothing step was not performed.

(20) TABLE-US-00001 TABLE 1 Example Example Example Example Example Example Comparative Comparative Comparative Comparative 1 2 3 4 5 6 Example 1 Example 2 Example 3 Example 4 Sheet smoothing Per- Per- Per- Per- Per- Per- Not Not Not Not step formed formed formed formed formed formed performed performed performed performed Surface for Front Rear Front Rear Front Rear Front Rear Front Rear measurement surface surface surface surface surface surface surface surface surface surface Thickness (mm) 3.0 3.0 1.5 1.5 1.5 1.5 3.2 3.2 1.7 1.7 Weight per unit 900 900 600 600 500 500 900 900 500 500 area (g/m.sup.2) Arithmetic surface 1.20 1.85 1.19 2.21 1.35 2.41 2.85 10.31 2.59 4.67 roughness (m) Crystallization 25 24 24 24 95 24 8 10 7 8 degree (%)

(21) In addition, when the formed sheet of Examples 1 to 6 was used as the core material and it was laminated with the fiber-reinforced resin sheet, there was not remarkable disorder in the fibers of the substrate sheet. However, when the expanded sheet of Comparative Examples 1 to 4 was used as the core material and was laminated with the fiber-reinforced resin sheet, there was disorder in a wave shape in the fibers of the substrate sheet at the interfacial side with the core material.

(22) As such the above, it is apparent that the present invention can provide the resin composite having excellent strength.