Carbon fiber random mat and carbon fiber composite material

Patent metadata

Field	Value
Publication number	US-11053363-B2
Application number	US-201716307323-A
Country	US
Kind code	B2
Filing date	Jul 12, 2017
Priority date	Jul 15, 2016
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A random mat material including fiber bundles, said fiber bundles including fibers having an average fiber length of 5 to 100 mm, and having an average number N of fibers in the fiber bundle that satisfies:
1.5 × 10 5 D 2 < N < 4.5 × 10 5 D 2
wherein D is the average diameter of fibers in the fiber bundle, expressed in micrometers, and the standard deviation SD N of the number of fibers in a fiber bundle satisfies:

1,000<SD N <6,000

wherein at an end of the fiber bundle, the number of the fibers in a fiber bundle becomes less from center to edge of the fiber bundle in a fiber direction.

First claim

The invention claimed is:

1. A method of producing a random mat comprising fiber bundles, said fiber bundles comprising fibers, said method comprising:
(i) cutting a fiber bundle at essentially constant intervals with a cutting roll having a rotational speed vc, wherein
100 RPM< vc< 400 RPM, and

a cutting edge has a diagonal angle θ with respect to the fibers direction; and
(ii) reducing the size of the fiber bundle, thereby providing the random mat.

2. The method according to claim 1 , wherein the fiber bundles comprise fibers having an average fiber length of 5 to 100 mm and has an average number N of fibers in the fiber bundle N that satisfies:

1.5
×

10
5

D
2

<
N
<

4.5
×

10
5

D
2

wherein D is the average diameter of fibers in the fiber bundle, expressed in micrometers, and the standard deviation SD N of the number of fibers in a fiber bundle satisfies:
1,000<SD N <6,000

and at an end of the fiber bundle, the number of the fibers in a fiber bundle becomes less from center to edge of the fiber bundle in a fiber direction.

3. The method according to claim 1 , wherein the fiber bundles satisfy:
2,000<SD N <6,000.

4. The method according to claim 1 , wherein the size of the fiber bundle is reduced by a stretching roll that is placed a distance L of 5 to 100 mm from a cutting roll, said cutting roll rotating at a rotational speed vc, said stretching roll rotating at a rotational speed vr; wherein vr is larger than vc.

5. The method according to claim 4 , wherein the ratio of vr/vc satisfies:
20< vr/vc< 80.

6. The method according to claim 4 , wherein the roll is cylindrically or conically shaped.

7. The method according to claim 1 , wherein 12K or 24K carbon fiber bundles are cut at step (i).

8. The method according to claim 1 , wherein the mat is coated with a thermoset or thermoplastic polymer film or powder.

9. A composite material comprising the random mat according to the method defined in claim 1 .

10. A molded fiber-reinforced article, wherein said molded fiber-reinforced article comprises one or more random mats according to claim 1 , said molded fiber-reinforced article comprises 10 to 65% by mass of the fiber bundle with respect to the total mass of said fiber-reinforced article.

Assignees

• Toray Industries

Inventors

• Geli Maurice
• Buzare Yann
• Karaki Takuya
• Taketa Ichiro

Classifications

• D04H1/4209 Primary

  Inorganic fibres · CPC title

• D04H1/4242

  Carbon fibres · CPC title

• C08J5/042 Primary

  with carbon fibres · CPC title

• D04H1/4342

  Aromatic polyamides · CPC title

• C08J2377/06

  Polyamides derived from polyamines and polycarboxylic acids (C08J2377/10 takes precedence) · CPC title