# US 5,346,930 A · Rigid fiberboard

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- Number: US 5,346,930 A
- Document ID: US5346930A
- Status: Granted
- Kind: A
- Application number: 08/048,677
- Filed: 1993-04-19
- Granted: 1994-09-13
- Earliest claimed: 1991-06-13
- Assignees: Lydall, Inc.
- Inventors: Richard L. Maine; Joseph W. Cook
- Web page: https://patentgrep.com/patent/US5346930A

## CPC

- B27N 3/04: from fibres
- B43K 19/14: Sheathings
- Y02P 20/582: Recycling of unreacted starting or intermediate materials
- B27N: MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL (containing cementitious material B28B; shaping of substances in a plastic state B29C; fibreboards made from fibrous suspensions D21J; drying F26B17/00)
- B43K: IMPLEMENTS FOR WRITING OR DRAWING (containers, casings or accessories for cosmetic substances, e.g. shaving soap, lipstick, make-up A45D34/00, A45D40/00)
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A rigid fiberboard suitable as a replacement for the natural woods presently used for the manufacture of pencils is provided. The fiberboard essentially comprises a fiber network, together with a filler and binder. A lubricant is added to improve the sharpening characteristics of the fiberboard, and dimensional stability is preserved by incorporating a waterproofing agent to minimize the absorption of water by the fiber network.

## Claims

### Claim 1

A pencil slat, comprising:
(A) about 38% to 75% of wet-laid recycled cellulose fibers recovered from recycled materials selected from the group consisting of recycled papers, linters, rags and mixtures thereof;
(B) about 10% to 30% of organic, particulate filler selected from the group consisting of corn cob flour, corn starch, rice hull flour, nut shell flour, fruit pit flour, wood flour, cork dust and mixtures thereof;
(C) a sufficient amount of thermosetting binder to provide rigidity to the pencil slat and within the range of about 10% to 35%, said binder being selected from the group consisting of phenolic resins, melamine resins, urea-formaldehyde resins, epoxy resins and mixtures thereof; and
(D) a sufficient amount of lubricating agent to allow a pencil made with said slat to be smoothly sharpened and within the range of about 2% to 15%, said lubricating agent being selected from the group consisting of polyethylene powder, wax, talc, stearates, fatty acids and mixtures thereof.

### Claim 2 (depends on 1)

The pencil slat of claim 1 wherein the cellulose fibers are recovered from recycled papers, the filler is selected from the group consisting of wood flour, cork dust and mixtures thereof, the binder is a phenolic resin, and the lubricating agent is selected from the group consisting of wax, stearic acid and mixtures thereof.

### Claim 3 (depends on 2)

The pencil slat of claim 2 wherein the waterproofing agent is wood rosin.

### Claim 4 (depends on 2)

The pencil slat of claim 2 wherein the papers are selected from the group consisting of recycled newspapers, corrugated boxes, cardboard, kraft papers and mixtures thereof.

### Claim 5 (depends on 1)

The pencil slat of claim 1 further including a dye.

### Claim 6 (depends on 1)

The pencil slat of claim 1 wherein the binder contains phenolic resin.

### Claim 7 (depends on 1)

The pencil slat of claim 1 further containing a retention aid.

### Claim 8 (depends on 7)

The pencil slat of claim 7 wherein the retention aid is a polyamide resin.

### Claim 9 (depends on 1)

The pencil slat of claim 1 having machinability and low moisture absorption at least substantially equal to a pencil slat made of natural incense cedar wood.

### Claim 10 (depends on 1)

A pencil made of pencil slats as defined in claim 1.

### Claim 11 (depends on 10)

The pencil of claim 10 having sharpening characteristics at least substantially equal to a pencil made of natural incense cedar wood.

### Claim 12 (depends on 1)

The pencil slat of claim 1, including a sufficient amount of a waterproofing agent to reduce water absorption of the slat such that dimensional stability thereof is preserved and within the range of about 0.4% to 1.5%, said waterproofing agent being selected from the group consisting of wood rosin and silicone-based water repellents.