WO2000006307A1 - Method for preserving porous materials - Google Patents

Abstract

The present invention relates to a method for preserving porous materials, mainly paper, that involves precipitating polyparaxylylene from a gaseous phase. This preservation method essentially involves heating diparaxylene and/or derivatives thereof in order to sublime it, and pyrolysing the same in a vacuum chamber. The pyrolysis products are then polymerised and a conformal polyparaxylylene coating is formed on the material. Before carrying out the sublimation heating, the substrate (porous material mainly consisting of paper) is treated in this same chamber using gaseous morpholine in the presence of steam. The morpholine vapours (tetrahydro-1,4-oxazine, diethylenimidoxide C4 H9 NO) are used as a neutralising agent and the treatment is carried out using a 50 % morpholine solution in an amount depending on the acidity (pH) and the type of the material to be preserved. The preservation of porous materials according to this method not only protects them against the environment harmful activity and increases their strength, but also imparts to the above-mentioned characteristics the stability necessary for a long-term preservation.

Description

\УΟ 00/06307

Method of acceptance of mathematical scientists Field of engineering

The invention relates to the preservation of porous materials, primarily paper, by applying a polymer coating by depositing poly-vapor-xylene (PVX) from a gas phase.

10

Previous level

The use of polymer coatings of materials for the purpose of protecting them from environmental influences, increasing their strength and durability is known [1, 2, 3].

15 A method for preserving porous materials is known, including heating with sublimation in a vacuum of di-para-xylene and/or its derivatives, treating the material with an inert gas, pyrolysis of di-para-xylene vapors, deposition and polymerization of the pyrolysis products on the material with The formation of poly-papa-strong experience. [4,5].

20 Application of PPC creates, in addition to protecting porous materials from moisture, a significant strengthening effect.

However, in the process of formation, a decrease in strength indicators is observed, especially for composites with PPC based on materials with increased acidity. Thus, in the process of accelerated

25 temperature-humidity state (at a temperature of 90°C and 50% relative humidity) the mechanical strength indicators of composites based on acidic types of paper with PPC decrease to a level of values corresponding to the mechanical strength indicators The strength of the paper is not covered by the PPC. This is due to the fact that in \ΥΟ 00/06307 ΡСΤ/Κυ98/00263

The presence of acid accelerates the oxidative degradation of paper-PPC composites [6].

It is known that in order to increase the durability of paper documents, when applying a PPC coating, the acidity of the paper is neutralized with ammonia [7,8]

The method of neutralizing the acidity of a porous material such as paper with ammonia is described in scientific papers [9,10,11]. However, based on the concept of the mechanism of interaction of ammonia with acids, it can be stated that this method provides only a 10-fold increase in the pH of the paper, since the resulting ammonia salts will, in turn, undergo hydrolysis according to formula:

ΝΗ ₄ С1 + Η ₂ Ο - Νы- ΟΗ + ΗСΙ <-^ΤΝΗ ₃ + Η ₂ Ο

15

As can be seen from the formula, due to the volatility of ammonia, the equilibrium will be shifted to the right and, consequently, an alkaline reserve will not be formed.

A method for neutralizing paper acidity with morpholine is known.

20 [12,13], which, in our opinion, more successfully provides the necessary alkaline reserve.

The problem that the claimed invention is aimed at solving is the preservation of the protective properties and the strengthening effect of the coating of the PPC during the process of long-term burning, that is, the

25 specified properties of composite materials - plastic material

(mainly paper) + ISHK necessary for preserving stability.

Discovery of inventions

30 The essence of the claimed technical solution is that in order to ensure the stability of the properties of composites of porous material \νθ 00/06307 ΡСΤЛШ98/00263

(mainly paper) with PPC pre-neutralizes (deacidifies) the porous material. According to the invention, morpholine (tetrahydro-1,4-oxazine, diethyleneimidoxide C ₄ H NO) is used as a neutralizing agent. Amine group

5 morpholine binds acid, as a result of which the stability of composites of porous materials with PPC increases.

According to the invention, a method for preserving porous materials, including heating with sublimation and vacuum pyrolysis of di-para-xylylene and/or its derivatives with subsequent precipitation and

10 by the polymerization of the pypilysis pathways and the formation on the basis of mathematics of many products from the PPK [4], i.e. obtaining a composite - porous material + PPC, a stage of processing the porous material with a gas-like morpholine in the presence of water vapor was introduced.

Before applying the PPC coating to the sublimation unit section

15 installations for obtaining PPC coatings, place a certain amount of 50% morpholine solution in water, which evaporates within 3-30 minutes, at a pressure of about 133 Pa. After the end of evaporation at a residual pressure of 7÷14 Pa, di-para-oxylene is sublimated and a coating is formed on the substrate.

20 The amount of moline consumed depends on the acidity of the material to be preserved, which clearly demonstrates the meanings set out below.

The method is implemented using a setup described in the literature [14] for obtaining PPC coatings from a gas phase, which is distinguished by the fact that in

25 sublimation unit of di-para-xylylene we have introduced a section for placing morpholine. As a result, the installation for obtaining PPC coatings from the gas phase contains: a sublimation unit equipped with sections for placing di-para-xylylene and morpholine; a pyrolysis unit of gas-like di-para-xylylene; polymerization chamber (application of coating on

30 substrate); vacuum line; instrumentation and vacuum system. \ θ 00/06307

Industrial applicability

Indications of the implementation of the slow method.

We mean 1. Paper pieces made of sulphite cellulose (B-7) with adhesive and

5 fillers (see Table 1 for composition), having a pH of the aqueous extract of the original paper of 5.68, were treated with morpholine in a chamber from a vapor-gas phase (at a concentration of 10 ml and 20 ml of a 50% aqueous solution of morpholine per 100 l of chamber volume) before coating with PPC.

An accelerated assessment was carried out to assess stability.

10 temperature-humidity stage (26 days at a temperature of 90°C and 50% relative humidity). For comparison, samples of the composite were taken with the same paper without preliminary treatment.

Results of comparative studies of the properties of composite materials, such as: resistance to fracture (unit of measurement - number of doubles Pepegigov - part.

15 d.p.); tensile stress (unit of measurement - MPa); ρН of water extract; are given in Table 2. As follows from the given data, the samples that have undergone preliminary treatment with morpholine from the gas phase at the rate of 20 ml of a 50% aqueous solution of morpholine have the highest efficiency of preserving the strength indicators of the composite with B-7 paper.

20 YOY cameras.

TABLE 1.

25 \νθ 00/063 7

TABLE 2.

Example 2. Samples of paper made of sulphate cellulose (B-11) with rosin glue sizing (see Table 1 for composition), having a pH of the aqueous extract of the original paper of 5.84, were treated with morpholine in a vapor-gas phase chamber (concentration of 10 ml and 20

10 ml of 50% aqueous moline paste per 100 liters of cameo volume).

To assess the stability, an artificial temperature and humidity condition was carried out (26 days at a temperature of 90°C and 50% relative humidity). For comparison, samples of the composite were taken with the same paper without preliminary treatment.

15 The results of comparative studies of properties are presented in Table 3. As follows from the data presented, the highest coefficient of comparison of the accuracy indicators of composite resin with Β-11 paper has Samples of 20 ml of 50% aqueous molin paste per 100l cameos.

20 ννθ 00/06307 ΡСΤ/ΚШ8/00263

TABLE 3.

5 Example 3.

The fiber samples with increased acidity, sulphite cellulose and flax fiber, having the pH of the original fiber respectively: sulphite cellulose - 5.68 and flax fiber - 6.73, were treated with 0.01H and 0.005H sulfuric acid solution.

10 (H ₂ 80 ₄ ). Before coating with PPC, model fiber samples with a given acidity were treated with morpholine in a vapor-phase chamber, with a concentration of 20 and 50 ml of a 50% aqueous solution of morpholine per 100 l of chamber volume.

To assess stability, an artificial simulation was carried out

15 (12 days, 100 °C)

The results of comparative determinations of the pH of the aqueous extract are given in Table 4. As can be seen from the given data, for flax fiber, which has an initial pH close to neutral, it is sufficient to treat it with morpholine at a rate of 20 ml per 100 l of the chamber, whereas for

20 sulphite cellulose having an initial pH in the acid zone, at least 50 ml per 100 l of the chamber is required. TABLE 4.

*Concentration of 50% aqueous paste 5 molina, ml/Yuol kamepa

The best option for implementing the invention

10 The best results were achieved when implementing the proposed method in accordance with examples 1,2,3 using a 50% aqueous solution of morpholine at a concentration of 20-50 ml/100 ml of the chamber.

Thus, the preservation of the declared porous materials

15 not only allows you to protect against the harmful effects of shrinking soy but also increase the accuracy (which is important for auspicious aphotic and apotheological materials), but also to provide the indicated properties with the necessary stability in process prolonged scribbling.

20

Sources of information:

1. Patent ΦΡГ ϋЧз 2737792, MUKI Β 05 ϋ 3/10, 1978.

2. US Patent No. 3342754, MUKI 05 ϋ 3/00, 1969. \νθ 00/06307 ΡСΤ/ΚШ8/00263

3. US Patent No. 3500216, MUKI 05 ϋ 3/00, 1971.

4. US Patent No. 3429739, MUKI Β32 Β 27/12, 1976.

5. Ηitρгеу Β.1 // Κеδϊаугагара. 1990. Ν1 ΙΡ.48-68.

6. Vilesova M.S., Levashova L.G., Mukhin V.E., Mushkovsky V.B., 5 Saprikina N.N., Trulev Yu.I., ZhPKh, 1997, issue 7, pp. 1186-1190.

7. Patent ΡΦ Ν° 2080192, MUKI Β 05 ϋ 3/04, 1997.

8. S.A. Dobrusina, V.F. Kochkin, E.S. Chernina, N.I. Podgornaya, R.I. Gulyaeva. Increasing the durability of paper documents by applying a poly-η-xylylene coating / J. Appl. Chemistry.

10 1994. - T. 66., No. 7. - P.1199-1202.

9. Laη§lνе11 Ψ.Η. Τе Сοηсеδегνаύοη Βοοкδ аηά ϋοсшηеηι, bοηάοη. 1957. P.32-41.

10. Kashpasha 1P. ϋleϊеποϊϊοη аηсϊ Сοηδегνаϋοη οГ Раρег. 1962., No. 17, ρ.245-251.

15 11. δсϊеηсе ΙΌГ Сοηδегνягδ - ьοηάοη; E\ν Υοgk: Τе Сοηδегνаποη сύϊ, 1994. - Уοϊ. 2. С1еарηϊη§. - Ρ. 96-99. - (Сοηзегνаϋοη зсϊеηсе ΙеаСыη§ zeg.).

12. US Patent 3771958, MUKI Β 32 Β 27/12, 1973.

13. Β.Ρ. Ψаϊkeg "Μοгρбοϋηе άеаϊсϋisaiοη: οη οГ ΨьοΙе Βοοкδ" Ρgezegνaidyuη οϊ Ρaρег аηά ΡеχШеδ οι ^" Ηϊδугϊс аηсϊ ΑйϊδΙϊс νаϊIE ΙС.

20 ΨϊShatδ Εе. Αάν. Sits. δeg. (1977) 164.

¹⁴ ) Neνν Υοgk es: Sheu, 1989. - Υοϊ. 17. - P. 990-1025.

25

Claims

ν θ 00/06307 ΡСΤ/ΚШ8/00263 Concept of invention 5 1. A method for preserving porous materials, including heating with sublimation and pyrolysis in a vacuum chamber of di-para-xylylene and/or its derivatives, followed by polymerization of the pyrolysis products and the formation of a thick coating on the material poly-p-xylylene, which is distinguished by the fact that in the same chamber before the reaction 10 sublimations neutralize the material, and the neutralization is carried out with gaseous morpholine in the presence of water vapor. 2. Method 1.1, characterized by the use of 50% moline paste in water as a neutralizing agent. quantity, depending on acidity (acidity) and the type of material involved.