IE42192B1

IE42192B1 - A method of treating wood flour and a product so obtained for use as an anti-oxidant for stored glass plants

Info

Publication number: IE42192B1
Application number: IE260175A
Authority: IE
Original assignee: Siv Soc Italiana Vetro
Priority date: 1974-11-29
Filing date: 1975-11-28
Publication date: 1980-06-18
Also published as: FR2292562A1; IE42192L; DK538475A; GB1510188A; LU73882A1; FR2292562B1; BE836044A; NL7513881A; DE2553049A1; IT1023450B; CH614882A5

Abstract

Wood flour is treated by carrying out the following steps: preparation of an aqueous solution of a weak organic acid, treatment of the wood flour with the prepared solution and drying of the impregnated wood flour obtained, the absorbed moisture being completely removed. The wood flour obtained can be used as an interlayer in the packaging of glass plates.

Description

The present invention relates to a method of treating wood flour in its untreated state with an acid, and it also relates to the product deriving from such treatment, the product being used in crating, boxing and generally in the packing of glass plates.

It is known that in the glass industry an important problem is preventing the glass plates, placed in mutual contact when packed, from undergoing oxidation, which is generally caused by the condensate which forms between adjacent plates, which oxidation causes an iridescent colouration or a staining of the contacting glass plates.

The attempts so far made to solve this problem consist in interposing between adjacent glass plates suitable separating elements such as sheets of paper, wood flour or synthetic flour.

Unfortunately, these systems are affected by various drawbacks of a practical, functional and economic order. In fact, the use of sheets of paper as separating elements between glass plates, although yielding satisfactory protective results, is completely uneconomical owing to the high cost of paper. Wood flour which has the advantage of being a low-cost product, does not possess a sufficient anti-oxidizing power when used without particular treatments and the use of synthetic flours, although they are also products of low-cost, has the inconveniehce that, in addition to having a low protective power against oxidation, they often cause adjacent glass plates to stick to each other or to become stained. - 2 42192 It is the object of the present invention to provide a very inexpensive product, which is characterised by excellent anti-oxidant properties, for use as an element of interposition between adjacent glass plates, particularly when they are packed together.

According to the present invention a method of treating wood flour to produce a product for preventing oxidation of glass plates comprises thoroughly impregnating untreated wood flour with an aqueous solution of a weak organic acid and heating the so impregnated wood flour until the water content of the solution has ' evaporated, thereby leaving acid-treated wood flour.

Weak organic acids which are particularly suitable in the treatment process of the present invention are oxalic acid, acetic acid and salicylic acid.

The examples which follow have the purpose of illustrating in greater detail the procedure of treating the wood flour according to the present invention.

EXAMPLE 1.

An aqueous solution containing IOS by weight of oxalic acid is prepared, with which a given amount of untreated wood flour is impregnated so that it is completely wetted. The so imbibed wood flour is placed in an oven at 105°C and left drying until the water content of the acid solution has evaporated.

The wood flour so treated is placed between six glass plates of 30 x 30 cm. which are joined together to form a package by means of rubber bands. For the purpose of comparison another package of six similar glass plates is prepared with wood flour in its untreated state interposed between adjacent plates. The two packs of glass plates are placed in a constant humidity chamber at 45-50°C, at a relative humidity of 100%. After approximately 2 months the packs are removed from the constant humidity chamber, dried in an oven at 50°C and thereafter each glass plate is washed in water.

As a result it is noted that a glass plate packed with wood flour treated according to the procedure of the present invention has surfaces which are - 3 4219 2 -?a/’ ? •’4*.?* oxidized in a negligible measure while the surfaces of the glass plates packed with wood flour in its untreated state are heavily oxidized.

The X by weight of oxalic acid in the aqueous solution can be front 5 to 10% inclusive.

EXAMPLE 2.

Untreated wood flour is treated as in Example 1 but using, in lieu of oxalic acid, a 5 volume % aqueous solution of acetic acid thoroughly to impregnate the wood flour. The wood flour so treated is interposed between six 30 x 30 cm. glass plates which are joined by rubber bands to form a package.

For the purpose of a comparison another package of six similar glass plates is formed by interposing wood flour in its natural state between adjacent plates.

The two packages of glass plates so made are placed in a constant humidity chamber at 45-50°C at a relative humidity of 100%. After approximately 3 months the packages are removed from the constant humidity chamber, dried in an oven at 50°C and thereafter each plate is washed with water.

The glass plates between which the wood flour treated with acetic acid was placed, show surfaces with a beginning of oxidation in some points while the glass plates between which wood flour in its untreated state had been placed are heavily oxidized.

A 5. to 15 volume % of acetic acid can be used in the aqueous solution.

EXAMPLE 3.

Three separate quantities of wood flour are prepared, each treated as in Example 1 but respectively impregnated with a 5 weight % aqueous solution of oxalic acid, with a 5 volume % aqueous solution of acetic acid and with a 5 weight % aqueous solution of salicylic acid. In the manner precedently described, packages of glass plates are prepared, each comprising 8 glass plates of 30 x 30 cm in the following combinations: a) glass plates without any element of interposition; b) glass plates with interposition of paper sheets; - 4 4219a c) glass plates with interposition of wood flour in the untreated state; f d) glass plates with interposition of wood flour treated with a 5 weight % aqueous solution of oxalic acid; e) glass plates with interposition of wood flour treated with 5 volume % aqueous solution of acetic acid; f) glass plates with interposition of wood flour impregnated with a 5 weight % aqueous solution of salicylic acid.

For each combination four batches were formed and each batch was placed in the following conditions; - batch 1 - packages placed in constant humidity chamber at a temperature of 45 - 50°C at 100% relative humidity; - batch 2 - packages with previously wetted glass plates and left at room temperature; - batch 3 - packages with glass plates which had been previously cleaned with pumice and alcohol, placed for 2 days in a constant-humidity chamber and thereafter at room temperature; - batch 4 - packages with glass plates not subjected to a cleaning treatment, placed for 2 days in a constant-humidity chamber and thereafter at room temperature.

After 16 days the glass plates of each package for each combination and for each batch have been examined, and the results obtained are listed in the following Table 1. - 5 42192 TABLE 1.

Batch Combination Degree of oxidation 1 a very hi gh b II 11 c 11 II d negligible e II f limited 2 a very high b II II c ii ii d negligible e II f limited 3 a limited b II c II d negligible e almost nil f negligible 4 a very high b U II c limited d negli gi ble e II f limited - 6 43l«i The aqueous solution can contain from 5 to 10% by weight of salicylic acid.

An important feature of the treatment of the wood flour according to the procedure of the present invention consists in the considerable lowering of the pH value, as shown in the Examples of the following Table 2.

TABLE 2.

Wood flour treated with: pH Oxalic acid in 5 weight % aqueous solution 1.9 acetic acid in 5 volume % aqueous solution 4.3 salicylic acid in a 5 weight % aqueous solution 4.5 wood flour in the natural state 6.4

Claims

1. A method for treating wood flour to produce a product for preventing oxidation of glass plates, comprising thoroughly impregnating untreated wood flour with an aqueous solution of a weak organic acid and heating the so impregnated wood flour until the water content of the solution has evaporated thereby leaving acid-treated wood flour. A method as claimed in Claim 1, wherein the acid used is oxalic acid in aqueous solution of 5-10% by weight of oxalic acid, A method as claimed in Claim 1, wherein the acid used is acetic acid in aqueous solution of 5-15 volume Ί, of acetic acid. A method as claimed in Claim 1, wherein the acid used is salicyl ic acid an aqueous solution from 5-10% by weight of salicyl lie acid. Acid-treated wood flour produced by the method of Clai m 1. - 7 4 219 2

2. 6. A method as claimed in any one of Claims 1 to 4 wherein the impregnated wood flour is heated to at least 105°C to evaporate said water content.

3. 7. A method according to Claim 1 for treating wood flour subatantially as hereinbefore described.