IP Library Granted Patent US 12679951
Granted Patent B2
US 12679951 · App. 17/839,435 · Granted Jul 14, 2026

Resin molded body and resin molded body production method

Inventors: Yujiro Hamada (Tokyo, JP); Yudai Motomatsu (Tokyo, JP); Masahiko Ono (Tokyo, JP)
Assignee: Mitsubishi Chemical Corporation
C08K5/20B29C45/0001B29C45/62B29C45/78C08F120/14B29C2945/7604B29K2233/12
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Quick Facts
Patent No.
US 12679951
App. No.
17/839,435
Granted
Jul 14, 2026
Kind
B2
Abstract

Provided is a resin molded product having excellent scratch resistance. The resin molded product of the present invention is a resin molded product including a methacrylic-based resin composition, in which the methacrylic-based resin composition contains a (meth)acrylic-based polymer (A) and a fatty acid compound (B), and an absorbance ratio P1/P2 of a peak absorbance P1 in a wave number range of 1630 to 1650 cm −1 to a peak absorbance P2 in a wave number range of 1710 to 1730 cm −1 on a surface of the resin molded product, measured by a single reflection ATR surface reflection method with an infrared spectrophotometer, is 0.0040 or more.

Claims (39)

1 . A resin molded product comprising:

a methacrylic-based resin composition,

wherein the methacrylic-based resin composition contains a (meth)acrylic-based polymer (A) and a fatty acid compound (B),

an absorbance ratio P1/P2 of a peak absorbance P1 in a wave number range of 1630 to 1650 cm −1 to a peak absorbance P2 in a wave number range of 1710 to 1730 cm −1 on a surface of the resin molded product, measured by a single reflection ATR surface reflection method with an infrared spectrophotometer, is 0.0040 or more,

the (meth)acrylic-based polymer (A) includes 70% by mass or more of a repeating unit derived from methyl methacrylate with respect to 100% by mass of a total mass of the (meth)acrylic-based polymer, and

a content ratio of the fatty acid compound (B) is 1% by mass or more and 10% by mass or less with respect to 100% by mass of a total mass of the methacrylic-based resin composition.

2 . The resin molded product according to claim 1 , wherein the fatty acid compound (B) is represented by General Formula (i),

R—CONH 2   (i)

in Formula, R is a hydrocarbon group having 10 to 25 carbon atoms which may have a substituent.

3 . The resin molded product according to claim 1 , wherein a dynamic friction coefficient of the surface of the resin molded product is 0.12 or less.

4 . The resin molded product according to claim 1 , wherein a water contact angle of the surface of the resin molded product is 69.0 degrees or higher.

5 . The resin molded product according to claim 1 , wherein a 10% weight-reduction temperature of the fatty acid compound (B) is 308° C. or lower.

6 . The resin molded product according to claim 1 , wherein the fatty acid compound (B) has a melting point of 90° C. or higher.

7 . The resin molded product according to claim 1 wherein the fatty acid compound (B) is a fatty acid amide compound (B1).

8 . The resin molded product according to claim 7 , wherein the fatty acid amide compound (B1) is a saturated fatty acid amide compound.

9 . The resin molded product according to claim 8 , wherein the saturated fatty acid amide compound contains stearic acid amide and palmitic acid amide as main components.

10 . The resin molded product according to claim 1 , wherein a solubility parameter of the fatty acid compound (B) is 11.0 (cal/cm 3 ) 1/2 or less.

11 . The resin molded product according to claim 1 , wherein the methacrylic-based resin composition does not contain a compound containing a fluorine atom.

12 . A vehicle member or a mobile phone member comprising the resin molded product according to claim 1 .

13 . The vehicle member according to claim 12 , wherein

the vehicle member is at least one selected from a tail lamp cover, a headlamp cover, and a meter panel.

14 . The mobile phone member according to claim 12 , wherein

the mobile phone member is a back plate of a mobile phone.

15 . A method of producing the resin molded product of claim 1 obtained by performing injection molding on a methacrylic-based resin composition containing a (meth)acrylic-based polymer (A) and a fatty acid compound (B), wherein

in the injection molding, the (meth)acrylic-based resin composition is injected from an injection molding machine with a cylinder temperature of 248° C. or higher and 300° C. or lower into a metal mold.

16 . The method of producing a resin molded product according to claim 15 ,

wherein the cylinder temperature of the injection molding machine is 248° C. or higher and 295° C. or lower.

17 . The method of producing a resin molded product according to claim 15 , wherein the cylinder temperature of the injection molding machine is 265° C. or higher and 290° C. or lower.

18 . The method of producing a resin molded product according to claim 15 , wherein the methacrylic-based resin composition is injected into the metal mold whose metal mold temperature is set in advance to 35° C. or higher and 90° C. or lower.

19 . The method of producing a resin molded product according to claim 15 , wherein the methacrylic-based resin composition is injected into the metal mold whose metal mold temperature is set in advance to 36° C. or higher and 70° C. or lower.

20 . The method of producing a resin molded product according to claim 15 , wherein the methacrylic-based resin composition is injected into the metal mold whose metal mold temperature is set in advance to 37° C. or higher and 50° C. or lower.

21 . The method of producing a resin molded product according to claim 15 , wherein in the injection molding, an injection speed is 30 cm 3 /sec or less.

22 . The method of producing a resin molded product according to claim 15 , wherein in the injection molding, an injection speed is 12 cm 3 /sec or less.

23 . The method of producing a resin molded product according to claim 15 , wherein in the injection molding, an injection speed is 8 cm 3 /sec or less.

24 . The method of producing a resin molded product according to claim 15 , wherein in the injection molding, an injection speed is 5 cm 3 /sec or less.

25 . The method of producing a resin molded product according to claim 15 , wherein a 10% weight-reduction temperature of the fatty acid compound (B) is 308° C. or lower.

26 . The method of producing a resin molded product according to claim 15 , wherein the fatty acid compound (B) has a melting point of 90° C. or higher.

27 . The resin molded product according to claim 1 , produced by injecting the (meth)acrylic-based resin composition from an injection molding machine with a cylinder temperature of 248° C. or higher and 300° C. or lower into a metal mold.

28 . The resin molded product according to claim 1 , produced by injecting the (meth)acrylic-based resin composition from an injection molding machine into a metal mold at an injection speed of 30 cm 3 /sec or less.