Porous poly(vinyl acetal) object and nonwoven poly(vinyl acetal) fabric

Abstract

The present invention aims to provide a porous polyvinyl acetal object and a nonwoven polyvinyl acetal fabric each capable of exhibiting significantly high shock absorption. Provided is a porous polyvinyl acetal object having a large number of cells, including: a polyvinyl acetal; and a plasticizer, the porous object having an open cell ratio of 10% or higher, the porous object in the form of a sample with a size of 10 cm in length, 10 cm in width, and 4 mm in thickness having a coefficient of rebound (rebounding height/drop height) of 0.1 or lower in measurement of a rebounding height of a -inch SUS ball in conformity with JIS B 1501 dropped from a given drop height to the center of the sample placed on an iron plate with a size of 10 cm or more in length, 10 cm or more in width, and 1 cm in thickness.

Claims

1. A porous polyvinyl acetal object having a large number of cells, comprising: a polyvinyl acetal; and a plasticizer, the porous object having an open cell ratio of 10% or higher, the porous object in the form of a sample with a size of 10 cm in length, 10 cm in width, and 4 mm in thickness having a coefficient of rebound (rebounding height/drop height) of 0.1 or lower in measurement of a rebounding height of a -inch SUS ball in conformity with JIS B 1501 dropped from a given drop height to the center of the sample placed on an iron plate with a size of 10 cm or more in length, 10 cm or more in width, and 1 cm in thickness.

2. The porous polyvinyl acetal object according to claim 1, wherein the open cell ratio is 14% or higher.

3. The porous polyvinyl acetal object according to claim 1, wherein the cells have an average cell size of 100 to 1,000 m.

4. The porous polyvinyl acetal object according to claim 1, wherein the cells have an average aspect ratio of 2 or less.

5. The porous polyvinyl acetal object according to claim 1, wherein the specific gravity thereof is 0.3 or less.

6. The porous polyvinyl acetal object according to claim 1, which is foamed with a heat-decomposable foaming agent.

7. A sound insulation material comprising the porous polyvinyl acetal object according to claim 1.

8. A vibration absorption material comprising the porous polyvinyl acetal object according to claim 1.

9. A shock absorption material comprising the porous polyvinyl acetal object according to claim 1.

10. A nonwoven polyvinyl acetal fabric comprising a fiber containing a polyvinyl acetal and a plasticizer, the nonwoven fabric having a weight per unit area of 100 to 800 g/m.sup.2, the nonwoven fabric in the form of a sample with a size of 10 cm in length, 10 cm in width, and 4 mm in thickness having a coefficient of rebound (rebounding height/drop height) of 0.1 or lower in measurement of a rebounding height of a -inch SUS ball in conformity with JIS B 1501 dropped from a given drop height to the center of the sample placed on an iron plate with a size of 10 cm or more in length, 10 cm or more in width, and 1 cm in thickness.

11. A sound insulation material comprising the nonwoven polyvinyl acetal fabric according to claim 10.

12. A vibration absorption material comprising the nonwoven polyvinyl acetal fabric according to claim 10.

13. A shock absorption material comprising the nonwoven polyvinyl acetal fabric according to claim 10.

Description

DESCRIPTION OF EMBODIMENTS

(1) Embodiments of the present invention are more specifically described in the following with reference to, but not limited to, examples.

Example 1

(2) To 100 parts by weight of polyvinyl butyral 1 (PVB1) were added 40 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer, 8.4 parts by weight of CELLMIC CAP as a heat-decomposable foaming agent, and 1.4 parts by weight of carbon black. The resulting mixture was sufficiently kneaded with a mixing roll at 110 C. and then extruded from an extruder into a sheet.

(3) The obtained sheet was placed in an oven and the heat-decomposable foaming agent therein was decomposed at a foaming temperature of 230 C. Thus, a porous object was obtained.

(4) Here, PVB1 had a hydroxy group content of 30 mol %, a degree of acetylation of 1 mol %, a degree of butyralization of 69 mol %, and an average degree of polymerization of 1,700. CELLMIC CAP is available from Sankyo Kasei Co., Ltd. and has a decomposition temperature of 125 C. The carbon black used is SEAST SP available from Tokai Carbon Co., Ltd.

(5) The open cell ratio of the obtained porous object was measured by pycnometry in conformity with JIS K7138. The average cell size and the average aspect ratio of cells were measured as follows by microscopic observation of void spaces. The apparent density was obtained by calculation based on the apparent volume obtained from size measurement and the measured weight. The specific gravity was obtained by calculation based on the apparent volume obtained from size measurement and the measured weight.

(6) (Measurement of Average Cell Size)

(7) A porous object sample for measurement was cut to a size of 50 mm in length, 50 mm in width, and 4 mm in thickness and immersed in liquid nitrogen for one minute. Then, the sample was cut along a plane parallel to the thickness direction using a razor blade.

(8) A magnified photograph (200) of the cut plane was taken using a digital microscope (VHX-900 available from Keyence Corporation), and the cell size of every cell present in the cut plane within a range of 2 mm in length in the thickness direction was measured.

(9) The same operation was repeated five times at different measurement sites, and the average of all the cell sizes measured in the observation was taken as the average cell size.

(10) The cell size of each cell was determined as the diameter of the largest circle inscribed in the cell.

(11) (Average Aspect Ratio of Cells)

(12) In the measurement of the average cell size, the major axis and minor axis of an ellipse inscribed in each cell observed were measured, and the aspect ratio was obtained by dividing the length of the major axis by the length of the minor axis. The aspect ratios of all the cells observed were obtained, and the average of the obtained aspect ratios was obtained.

Example 2

(13) A porous object was obtained as in Example 1, except that the foaming temperature was changed to 190 C.

Example 3

(14) A porous object was obtained as in Example 1, except that the amount of the heat-decomposable foaming agent was changed to 5.6 parts by weight.

Example 4

(15) A porous object was obtained as in Example 1, except that the heat-decomposable foaming agent used was 5.6 parts by weight of VINYFOR AC-K3 (available from Eiwa Chemical Inc. Co., Ltd., decomposition temperature of 210 C.).

Example 5

(16) A porous object was obtained as in Example 1, except that the amount of the plasticizer was changed to 20 parts by weight.

Example 6

(17) A porous object was obtained as in Example 1, except that the amount of the plasticizer was changed to 20 parts by weight and the heat-decomposable foaming agent used was 5.6 parts by weight of CELLMIC CAP.

Example 7

(18) A porous object was obtained as in Example 1, except that PVB1 was changed to polyvinyl butyral (PVB2, hydroxy group content of 23 mol %, degree of acetylation of 13 mol %, degree of butyralization of 64 mol %, average degree of polymerization of 2,400), the amount of the plasticizer was changed to 60 parts by weight, and the heat-decomposable foaming agent used was AC-K3.

Example 8

(19) As an interlayer film for a laminated glass, S-LEC Clear Film (S-LEC in tables) available from Sekisui Chemical Co., Ltd. was prepared. The interlayer film for a laminated glass was shredded to a size of 7 mm10 mm to prepare a recycling material.

(20) To 100 parts by weight of the obtained recycling material were added 6 parts by weight of CELLMIC CAP as a heat-decomposable foaming agent and 1 part by weight of carbon black. The mixture was sufficiently kneaded with a mixing roll at 110 C. and then extruded from an extruder into a sheet. The obtained sheet was placed in an oven and the heat-decomposable foaming agent therein was decomposed at a foaming temperature of 230 C. Thus, a porous object was obtained.

Example 9

(21) A porous object was obtained as in Example 3, except that the foaming temperature was changed to 190 C.

Example 10

(22) To 100 parts by weight of polyvinyl butyral (PVB1) were added 40 parts by weight of 3GO, 5.6 parts by weight of CELLMIC AN, 2.0 parts by weight of trimethylolpropane triacrylate (TMPTA), 0.4 parts by weight of benzophenone, and 1.4 parts by weight of carbon black, thereby preparing a resin composition. The obtained resin composition was sufficiently kneaded with a mixing roll at 110 C. and then extruded from an extruder into a sheet with a thickness of 1 mm. Both surfaces of the obtained sheet were irradiated with UV rays at a dose of 1,500 mJ/cm.sup.2 (365 nm) using a high-pressure mercury lamp (TOSCURE 401 available from Toshiba Lighting & Technology Corporation). Thus, benzophenone was activated to perform crosslinking. To both surfaces of the obtained crosslinked sheet was heat-welded a fluororesin net (NR0515 available from Flonchemical Co., Ltd., 18 mesh equivalent, thickness of 0.7 mm) at 60 C. The resulting sheet was placed in an oven and the heat-decomposable foaming agent was decomposed at a foaming temperature of 230 C., thereby allowing the sheet to foam. After the foaming, the fluororesin nets were removed. The volume was changed due to the foaming only in the thickness direction because elongation in the planar direction was prevented by the Teflon mesh. Thus, a porous object having rugby ball-shaped cells was obtained.

(23) CELLMIC AN is available from Sankyo Kasei Co., Ltd. and has a decomposition temperature of 125 C. TMPTA used was available from Tokai Carbon Co., Ltd. and the carbon black used was available from Tokai Carbon Co., Ltd.

Example 11

(24) To 100 parts by weight of polyvinyl butyral 1 (PVB1) was added 40 parts by weight of triethylene glycol di-2-ethylhexanoate (3GO) as a plasticizer, thereby preparing a resin composition. The obtained resin composition was sufficiently kneaded with a mixing roll and extruded from an extruder into strands with a diameter of 1 mm.

(25) The obtained strands were cut to a length of 10 cm and then randomly stacked to have a weight per unit area after thermal pressure bonding of 400 g/m.sup.2. The resulting stack was thermally pressure bonded using a press machine so that contact portions of the strands were thermally fused. Thus, a nonwoven fabric was obtained.

(26) Fibers constituting the obtained nonwoven fabric had an average diameter (average fiber diameter) of 1 mm that was the same as the diameter of each strand.

(27) The thermal pressure bonding was performed under the conditions of an interval between press plates of 4 mm, a press temperature of 130 C., and a press time of three minutes.

Example 12

(28) A nonwoven fabric was obtained as in Example 11, except that the strands were stacked to have a weight per unit area after thermal pressure bonding of 300 g/m.sup.2.

Example 13

(29) A nonwoven fabric was obtained as in Example 11, except that the strands were stacked to have a weight per unit area after thermal pressure bonding of 800 g/m.sup.2.

Comparative Example 1

(30) A commercially available polyethylene foamed article (Softlon S available from Sekisui Chemical Co., Ltd., expansion ratio of 30 times) was used as a comparative example.

Comparative Example 2

(31) A commercially available polyethylene foamed article (Softlon S available from Sekisui Chemical Co., Ltd., expansion ratio of 40 times) was used as a comparative example.

Comparative Example 3

(32) A commercially available polypropylene foamed article (Softlon SP available from Sekisui Chemical Co., Ltd., expansion ratio of 15 times) was used as a comparative example.

Comparative Example 4

(33) The polyethylene foamed article of Comparative Example 1 was subjected to perforation using a perforation roll with 150-micron-thick needles to have an open cell ratio of 50%.

Comparative Example 5

(34) A porous object was obtained as in Example 1, except that the foaming temperature was changed to 170 C.

Comparative Example 6

(35) A porous object was obtained as in Example 1, except that the amount of the heat-decomposable foaming agent was changed to 3.0 parts by weight.

(36) (Evaluation)

(37) The following evaluation was performed on the porous objects obtained in the examples and comparative examples. Tables 1 and 2 show the results.

(38) (Ball Drop Test)

(39) The porous objects and nonwoven fabrics obtained in the examples and comparative examples were each cut to a size of 10 cm in length, 10 cm in width, and 4 mm in thickness, thereby preparing measurement samples. Cutting in the length direction and the width direction was performed using a box cutter and adjustment of the thickness was performed using a band machine-slicer (Band machine NP-12ORS available from Nippy Kikai Co., Ltd.). When accurate cutting to a thickness of 4 mm is difficult, an average thickness of 4 mm0.1 mm was acceptable.

(40) The measurement sample was placed on an iron plate having a size of 15 cm in length, 15 cm in width, and 1 cm in thickness. A SUS ball (equivalent inch size: inch) in conformity with JIS B 1501 was dropped on the sample from heights of 10 cm, 20 cm, and 30 cm, and the rebounding heights were determined. Based on the obtained values, the coefficients of rebound (rebounding height/drop height) were calculated. The measurement was performed under a condition of 23 C. temperature and 50% Rh humidity.

(41) (Shock Absorption Test)

(42) The measurement samples having a size of 10 cm in length, 10 cm in width, and 4 mm in thickness were obtained by the same method as in the ball drop test.

(43) The measurement sample was placed on an iron plate having a size of 10 cm or more in length, 10 cm or more in width, and 1 cm in thickness. A closed Erlenmeyer flask with stopper (capacity: 10 mL, total height: 50 mm, maximum outer diameter: 30 mm) was vertically dropped to the sample from 20 cm or 30 cm above the sample in such a manner that the flask bottom hit the sample.

(44) This operation was continuously repeated 10 times, and the number of times the stopper did not come off due to the drop impact was recorded in Table 1 and Table 2.

(45) TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Material Thermoplatic Type PVB1 PVB1 PVB1 PVB1 PVB1 resin Amount Parts by weight 100 100 100 100 100 Plasticizer Type 3GO 3GO 3GO 3GO 3GO Amount Parts by weight 40 40 40 40 20 Foaming Type CELMIC CAP CELMIC CAP CELMIC CAP VINYFOR CELMIC CAP agent AC-K3 Amount Parts by weight 8.4 8.4 5.6 5.6 8.4 Others Type Carbon black Carbon black Carbon black Carbon black Carbon black Amount Parts by weight 1.4 1.4 1.4 1.4 1.4 Type Amount Parts by weight Type Amount Parts by weight Foaming temperature C. 230 230 230 230 230 Shape Shape Porous object Porous object Porous object Porous object Porous object Open cell ratio % 82 12 54 14 67 Apparent density kg/m.sup.3 104 199 130 200 112 Specific gravity 0.10 0.20 0.13 0.20 0.11 Avrage aspect ratio 1.3 1.1 1.2 1.1 1.1 Average cell size m 300 220 300 250 250 Weight per unit area g/m.sup.2 Ball drop Drop height Rebounding height cm 0.0 0.1 0.0 0.1 0.5 test 10 cm Coefficient of rebound 0.00 0.01 0.00 0.01 0.05 Drop height Rebounding height cm 0.2 0.5 0.3 0.5 1.2 20 cm Coefficient of rebound 0.01 0.03 0.02 0.03 0.06 Drop height Rebounding height cm 0.4 0.8 0.5 0.7 1.5 30 cm Coefficient of rebound 0.01 0.03 0.02 0.02 0.05 Evaluation Drop test of Erlenmeyer flask with stopper 10 10 10 10 10 (drop height of 20 cm) Drop test of Erlenmeyer flask with stopper 10 9 9 10 7 (drop height of 30 cm) Example 6 Example 7 Example 8 Example 9 Example 10 Material Thermoplatic Type PVB1 PVB2 S-LEC PVB1 PVB1 resin Amount Parts by weight 100 100 100 100 100 Plasticizer Type 3GO 3GO 3GO 3GO Amount Parts by weight 20 60 40 40 Foaming Type CELMIC CAP VINYFOR CELMIC CAP CELMIC CAP CELMIC AN agent AC-K3 Amount Parts by weight 5.6 8.4 6 5.6 5.6 Others Type Carbon black Carbon black Carbon black Carbon black Carbon black Amount Parts by weight 1.4 1.4 1 1.4 1.4 Type TMPTA Amount Parts by weight 2.0 Type Benzophenone Amount Parts by weight 0.4 Foaming temperature C. 230 230 230 190 230 Shape Shape Porous object Porous object Porous object Porous object Porous object Open cell ratio % 67 90 85 35 60 Apparent density kg/m.sup.3 251 94 113 295 153 Specific gravity 0.25 0.09 0.11 0.30 0.15 Avrage aspect ratio 1.2 1.2 1.1 1.1 1.8 Average cell size m 210 260 270 200 180 Weight per unit area g/m.sup.2 Ball drop Drop height Rebounding height cm 0.7 0.0 0.0 0.8 0.1 test 10 cm Coefficient of rebound 0.07 0.00 0.00 0.09 0.01 Drop height Rebounding height cm 1.5 0.2 0.3 1.6 0.4 20 cm Coefficient of rebound 0.08 0.01 0.02 0.08 0.02 Drop height Rebounding height cm 2.4 0.3 0.8 2.7 0.6 30 cm Coefficient of rebound 0.08 0.01 0.03 0.09 0.02 Evaluation Drop test of Erlenmeyer flask with stopper 10 10 10 9 10 (drop height of 20 cm) Drop test of Erlenmeyer flask with stopper 8 9 9 7 10 (drop height of 30 cm)

(46) TABLE-US-00002 TABLE 2 Comparative Example 11 Example 12 Example 13 Example 1 Material Thermoplastic Type PVB1 PVB1 PVB1 Polyethylene resin Amount Parts by weight 100 100 100 Plasticizer Type 3GO 3GO 3GO Amount Parts by weight 40 40 40 Foaming agent Type Amount Parts by weight Others Type Amount Parts by weight Foaming temperature C. Shape Shape Nonwoven fabric Nonwoven fabric Nonwoven fabric Porous object Open cell ratio % <1 Apparent density kg/m.sup.3 33 Specific gravity 0.033 Average aspect ratio 1.1 Average cell size m 200 Weight per unit area g/m.sup.2 400 300 800 Ball drop test Drop height Rebounding height cm 0.2 0.2 0.5 5.8 10 cm Coefficient of rebound 0.02 0.02 0.05 0.58 Drop height Rebounding height cm 0.5 0.4. 1.1 12.6 20 cm Coefficient of rebound 0.03 0.02 0.06 0.63 Drop height Rebounding height cm 0.7 0.6 1.4 16.2 30 cm Coefficient of rebound 0.02 0.02 0.05 0.54 Evaluation Drop test of Erlenmeyer flask with stopper 10 10 10 5 (drop height of 20 cm) Drop test of Erlenmeyer flask with stopper 7 7 5 2 (drop height of 30 cm) Comparative Comparative Comparative Comparative Comparative Example 2 Example 3 Example 4 Example 5 Example 6 Material Thermoplastic Type Polyethylene Polypropylene Polyethylene PVB1 PVB1 resin Amount Parts by weight 100 100 Plasticizer Type 3GO 3GO Amount Parts by weight 40 40 Foaming agent Type CELMIC CAP CELMIC CAP Amount Parts by weight 8.4 3.0 Others Type Carbon black Carbon black Amount Parts by weight 1.4 1.4 Foaming temperature C. 170 230 Shape Shape Porous object Porous object Porous Porous object Porous object object Open cell ratio % <1 <1 50 6 40 Apparent density kg/m.sup.3 25 62 33 153 450 Specific gravity 0.025 0.06 0.033 0.15 0.45 Average aspect ratio 1.2 1.1 1.1 1.1 1.0 Average cell size m 200 150 200 180 150 Weight per unit area g/m.sup.2 Ball drop Drop height Rebounding height cm 5.8 3.5 5.2 4.6 1.5 test 10 cm Coefficient of rebound 0.58 0.35 0.52 0.46 0.15 Drop height Rebounding height cm 11.5 6 12 10 3.4 20 cm Coefficient of rebound 0.58 0.3 0.6 0.5 0.17 Drop height Rebounding height cm 16.8 9.6 15.6 15.8 5.2 30 cm Coefficient of rebound 0.56 0.32 0.52 0.79 0.17 Evaluation Drop test of Erlenmeyer flask with stopper 4 3 3 4 7 (drop height of 20 cm) Drop test of Erlenmeyer flask with stopper 2 3 1 3 5 (drop height of 30 cm)

INDUSTRIAL APPLICABILITY

(47) The present invention can provide a porous polyvinyl acetal object and a nonwoven polyvinyl acetal fabric each capable of exhibiting significantly high shock absorption.