FI60266C - BEHANDLING AV AEMNEN MED SILIKONHALOGENIDER - Google Patents

Description

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juA ^ (11) UTLÄGGNI NGSSKRI FT 6 U 2 6 o (45) ia tent «Odd elät ^ T ^ (51) Kv.ik.3 / int.a.3 D 21 H 3/02, D 06 M 15 / 00 FINLAND — FINLAND (*> Puunttlhtktmui - Pat «ntani6knlng 76098l (22) Hkkamliptlvi - Arattknlnpdtg 09 · 04. 76 ^ ^ (23) Alkuptlvt - Glltlgh * t * d * g 09 · 04. offuntllg 10.10.76

National Board of Patents and Registration .... UlL, ...,. .....

'. . (44) Date of issue. - Oh, Oh

Patent and registration authorities 7 Amdkan utlagd och utl.tkrKtM publkurad J1.UO.OA

(32) (33) (31) Pyjrdutty utuoikuu * —B «glrd prloritet 09.0U.75 USA (US) 566220 (71) Dennison Manufacturing Company, 300 Howard Street, Framingham, Massachusetts 01701, USA (US) (72) Eugene E. Tompkins, Lexington, Massachusetts, USA (7 ^) Forssen & Salomaa Oy (5U) Treatment of substances with silicon halides - Behandling av ämnen med silikon-halogenider

The invention relates to a method for making a substance water-repellent without unacceptable acid decomposition.

It has been known for several years that substances can be treated with silicon halides to make them water repellent. Examples are disclosed in U.S. Patents 2,306,222 (1942); 2,386,259 (1945); and 2,412,470 (1946).

The halides react with hydroxyl groups, for example in the moisture of the substance to be treated, to form siloxanes which form a water-repellent film. The by-product of the reaction is hydrogen chloride gas, which can also react with moisture in the substance. The reaction produces hydrochloric acid, which is corrosive to most substances, especially those of a cellulosic nature.

Even if the moisture content of the substance to be treated is low, there is always a small amount of hydrogen chloride gas, especially if the substance is porous, which gas may have an adverse effect later on, when the treated substance comes into contact with or absorbs moisture.

An obvious way to eliminate a hydrogen chloride by-product is to neutralize it with, for example, ammonia as disclosed in U.S. Patent 2,306,222. Neutralization not only complicates the process but also generally requires a liquid bath and is therefore unsuitable for certain products such as paper.

In addition, previous neutralization attempts did not appear to produce a commercially acceptable product. Thus, U.S. Patent 2,824,778 (1958) stated: "Although there have been minor difficulties in making products water repellent, no method has been developed to date that does not cause severe degradation and loss of strength ... and none of the methods developed to date have achieved commercial success. . " U.S. Patent 2,824,778 (1958) said that the solution to the above difficulties is to "contact the cellulosic material with a gas mixture of silane and an inert gas under time and temperature conditions found suitable for the desired reaction between the material and the silane to cause decomposition. to avoid side reactions, and immediately or very soon thereafter neutralize the reaction by-products by immersing the material in a slightly alkaline solution. " The neutralization required in this method was shown to be avoidable in U.S. Patent 2,995,470 (1961) by providing a closed treatment zone through which aerosol vapors of treatment reagent usually flow in an ascending direction. In this case, the by-products were continuously removed from the reaction zone with an upward flow.

In a series of test runs, usually performed in accordance with U.S. Patent 2,995,470 (1961), spray nozzles were used to provide an upward flow of silane mixture. According to the report, the treated substance was water repellent, but the pH (hydrogen ionization potential) was so far in the acidic range (less than 3 on a scale of 1-14 where 7 is neutral) that the product was not considered satisfactory and was subject to unacceptable acid degradation.

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Furthermore, notwithstanding U.S. Patent 2,995,470 (1961), it was later mentioned (1969) in Canadian Patent 906,849 (1972): "Until now, in the treatment of cellulosic materials ... it has been necessary ". The decomposing effects of hydrogen halide by-products were said to be avoided by contacting the silica halide vapors with the substance to be treated in the presence of an inert solvent vapor. It was later disclosed in U.S. Patent 3,856,558 (1974) that the use of a solvent is a preferred embodiment.

According to the method described in the Canadian patent, the following experimental results were performed: Brown kraft paper with a moisture content of 7.99% by weight was pre-dried in an oven at about 150 ° C with a residence time of about 3 seconds to reduce the moisture content to about 5% by weight. The pre-dried paper was passed as a continuous feed through a chamber into which silane vapors were introduced using toluene as the inert solvent. The silane vapor was a mixture of 70% by weight of methyltrichlorosilane, 20% by weight of dimethyldichlorosilane and 10% by weight of methyldichlorosilane and was used at 1% by weight of paper. The inert solvent, toluene, was 20% by volume and 22 mol% of the total composition fed into the chamber. The residence time of the paper in the chamber was about 6 seconds in an atmosphere containing about 2% by volume of silane and toluene at room temperature. After the paper exited the treatment chamber, it was passed next to the radiant heaters to raise the surface temperature of the paper to about 90 ° C and subjected to air blowing. The sample was examined by placing it under a water tap and was found to be water repellent. However, the treatment method was completely unsatisfactory. In order to achieve an adequate reaction of the silane, it was necessary to completely close the outlet of the device, as a result of which the plant was filled with dangerous silane vapors. No tests were performed on tensile strength. From previous series of experiments using a solvent, it has been concluded that although the use of the solvent produced some improvement, the product obtained was still unsatisfactory because the pH was still so low that the researchers found the product unacceptable.

The invention thus relates to the treatment of substances as water-repellent without unacceptable acid decomposition. A related object is said processing 60266 in 4 commercial dimensions. The invention further relates to the treatment of substances for water repellency at high speed.

The invention further relates to the treatment of substances as water-repellent on a commercial scale without unacceptable acid decomposition and without the need for neutralization or an inert solvent. A related object is the treatment of substances as water repellents at relatively high pH so that neither neutralization nor solvent is necessary.

To accomplish the above and related objects, the invention is essentially characterized by the steps of: (a) injecting organo-halosilane vapors into the treatment chamber through which the substance passes, and (b) maintaining the vapors in non-laminar flow conditions for substantially the entire length of the chamber.

The desired non-laminar flow is achieved by designing the treatment chamber so that the highest possible Reynolds number is achieved under the treatment conditions. The higher the Reynolds number, the greater the turbulence of the steam flow. Reynolds numbers above about 1000-2000 in the range are non-laminar. Unlike the laminar flow used previously, the non-laminar flow according to the invention not only ensures that the desired degree of water repellency is achieved relatively quickly, but also provides an abrasion effect with respect to the hydrogen halide vapors formed as by-products. When used as previously described, the laminar flow had to take a considerable period of time before the material was sufficiently treated to achieve water repellency, and as a result, hydrogen chloride vapors were in contact with the material for a relatively long time and thus could adversely affect the long-term durability of the material.

One aspect of the treatment according to the invention is that water repellency is achieved relatively quickly when using a non-laminar flow, which allows the hydrogen chloride gas formed as a by-product to be removed before it can significantly adversely affect the substance to be treated.

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According to one aspect of the invention, the treatment time can be shortened by using nitrogen as the carrier gas.

According to a further aspect of the invention, the desired non-laminar flow is achieved by using a large number of small diameter injection orifices and by using barriers in the flow of treatment gases, such as baffles. The non-laminar flow is maintained during the treatment period so that the reaction zone is a narrow gap.

According to one aspect of the invention, an exhaust chamber with a low vacuum is placed at a point in the reaction zone where the reaction of the silicon halide has been sufficient to achieve water repellency but the hydrogen chloride reaction has been insufficient to cause decomposition.

In general, the moisture content of the substance to be treated, which may be cellulosic, may be in the range of 2 to 7% by weight. It is contacted with silicon halide vapors, including lower alkyl silicon vapors, for a period of about 0.1 second to 8 seconds. The treatment gases are believed to react with water to form siloxane. The silicon halide content and the treatment temperature are maintained such that the substance to be treated is rendered water-repellent at a pH greater than about 2.5.

In particular, the moisture content may be in the range of 3.5-6.5%, which includes in the range of 4-670 and is preferably in the range of 4.5-6.5%. The contact time may be in the range of 0.5 to 4 seconds, which includes the range of 0.5 to 1.5 seconds.

Other aspects of the invention will become apparent upon examination of several illustrative embodiments relating to the drawings, in which:

Fig. 1A is a diagram illustrating the treatment of materials according to the prior art using a laminar from a silicon halide stream;

Fig. 1B is a diagram illustrating the treatment of materials in accordance with the invention using a non-laminated silicon halide stream;

Fig. 2A is a perspective view of a processing apparatus for producing a non-laminar flow as shown in Fig. 1B; 6 6 0 2 6 6

Figure 2B is a perspective view of a supply gas manifold according to the invention;

Figure 3A is a graphical representation of the relationship between silicon halide and hydrogen chloride by-product formation in the apparatus of Figure 2A;

Figure 3B is a graphical representation of the relationship between water repellency and degradation in a treatment device according to the invention;

Figure 3C is a graphical representation of the pressure to length relationship in the device of Figure 2A; and

Figure 4 is a graphical representation of acceptable silane mixtures in a triangular coordinate system for treating materials as water repellent in accordance with the invention.

Figures Figure IA illustrates a sheet of material 10 which travels in the direction of the arrow and a laminar flow käsittelyhöyryjen 21 exposed. Under laminar flow conditions, only molecules close to the surface to be treated from the gas flow are able to react with the hydroxyl groups in the material to form the desired siloxane film. When the reaction takes place, chlorine-hydrogen gas marked with dashed lines 31 and circles 41 is formed. Some of the hydrogen chloride gas moves in the flow direction, but much of it remains on the surface of the substance, as shown by the circles 41 '. Due to the flow conditions of the laminars, the by-products are in such contact with the paper that they can remain in its slots, moving away only due to gas diffusion.

In the case of the invention, on the other hand, as shown in Figure 1B, the turbulent, non-laminar flow of reagents 22 brings a substantial amount of the silane mixture into contact with the surface of the material to be treated 10 and produces a faster reaction than the laminar flow. In addition, the vortex flow has an abrasive effect which transports the hydrogen chloride gas 32 formed as a by-product away from the surface to be treated, leaving only a small amount, marked with circles 42 ', on the surface.

It will be appreciated that the diagrams in Figures 1A and 1B only illustrate one possible explanation as to why the invention is capable of accomplishing what has been achieved by previous commercially successful companies over the past 20 years, and that the disclosure is not intended to limit the applicant's invention.

The treatment chamber 50 according to the invention is shown in Figure 2A. To provide the desired non-laminar flow, a series of barriers 51 are placed in the path of the silicon halide treatment vapor. In addition, the upper and lower blocks 52 and 53 of the chamber are as close together as possible, taking into account the requirements of the material 10 to be treated, for example the thickness of the web and the amount of vibration that occurs when the material is passed through the chamber 50. Close proximity of blocks 52 and 53 leaves a narrow path for material to pass.

It has been found that for cellulose sheets, a bus minimum of up to 0.8 mm can be achieved. The typical distance between the blocks in the processing chamber is in the range of 3.2-4.8 mm, but passages as wide as 25.4 mm are satisfactory.

The substance to be treated 10 is fed into the chamber through a barrier 60 formed by the flexible elastomeric parts 61 and 62. A suitable barrier is obtained from a fluoroelastomer sold and marketed by E.I. du Pont de Nemours & Company under the trade name "VITON".

Behind the barrier 60 are inlet gas manifolds 71 and 72 for injecting silicon halide vapors from the gas mixing chamber and tubes 73 and 74. The inlet gas manifold 71, detailed in Figure 2B, is a concept for injecting vapors to the other side of the plate 10. The second manifold 72 is on the opposite side 12.

In one device model, the tube 71 had a diameter D of 38.1 mm and 40 openings 75, each having a diameter of 1.6 mm and spaced 25.4 mm apart. In another device model, the tube 71 was 15.9 mm in diameter and had 8 openings 75 with a diameter of 2.4 mm and a distance of 25.4 mm from each other.

The treatment vapors come out of the two-compartment outlet unit 80. In the first compartment 81, a slight vacuum is maintained and the main outlet (to the gas scrubber) takes place via pipes 83 and 84. The additional outlet along the pipe 85 from the second compartment 82 takes place after the plate 10 has passed through a second barrier 60 ', which is similar to the inlet barrier 60.

The Reynolds number of the flow in chamber 50 is above the range of about 1000-2000. In general, the Reynolds number (RN) is according to Equation (1) 8 60 2 6 6 RN = (1) μ where d = equivalent flow diameter in the flow in the chamber 50 or in the orifices 75 v = gas flow rate through the equivalent diameter p = flow density μ = viscosity

In experiments according to a previously known method, the Reynolds numbers were found to be of the order of 10, which is well in the laminar region.

The chamber of Figure 2A is in contrast to those previously known, which had an open space for the passage of reagents, as it was believed that this was possible to quickly remove harmful hydrogen chloride vapors. Instead, as discussed above, the result was a laminar flow that required a long treatment time and thus allowed a relatively long lasting effect between the hydrogen chloride and the material to be treated.

In addition, the chamber 50 of Figure 2A can suitably treat relatively porous materials that, for example, could not be treated in the ways previously described, which require an ascending flow of treatment halide through the material in an effort to rapidly remove harmful vapors.

Curves a and b, which are believed to indicate the concentration of the silane mixture (a) over the length of the chamber and the relationship between the hydrogen chloride by-product (b), are shown in Figure 3A. At the feed point Lq, the silane mixture begins to react with the substance and the remaining amount decreases over the length of the chamber. The amount of hydrogen chloride increases with decreasing amount of silane mixture. There is a point L 1 where the necessary amount of silane has reacted to achieve water repellency and the amount of hydrogen chloride formed is still insufficient to adversely affect the material. Proceeding in length from point L2 to the treatment chamber, the silane mixture reacts continuously and improves the water repellency of the substance, but the amount of hydrogen chloride increases accordingly and point L2 is reached, where continuous exposure of the substance to hydrogen chloride would seriously damage the substance. Accordingly, the length of the processing chamber of Fig. 2A is such that the point between L 1 and L 2 ** n in Fig. 3A is obtained.

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Adjustments to achieve a satisfactory result between the points shown in Figure 3A and in between can also be made by varying the flow of gas mixed with silane vapors. Reducing the total volume of gas fed per unit time would obviously increase the residence time of the molecules in the treatment chamber and thus cause further reaction of the silanes.

Figure 3B is another graphical representation of the principle. For the length, the water repellency is sufficient, for L 1, the decomposition is not acceptable, therefore the length of the treatment chamber is chosen between L 1 and L 2.

Figure 3C is a graphical representation of the pressure «ί over the length of the chamber L ^ · This diagram shows that the outlet end (L ^) has a slight negative pressure which practically decreases to zero (or even a weak overpressure) at the inlet end (Lq).

The results of experiments to determine the effect of percentage variation in the various silane components are summarized in Figure A. In the resulting triangular coordinate system, the proportion of private silane component was 100% at each tip as shown, with this component gradually decreasing and possibly reaching zero along the axis. . The results shown in Figure A show that a mixture in the R range containing methyl trichlorosilane (CH 2 SiHCl 2) in the range up to about 70%; methyl dichlorosilane (CH 2 SiHCl 2) in the range up to about 65% and dimethyl dichlorosilane in the range up to about 80% can result in excellent good water repellency.

The moisture content of the material to be treated, e.g. paper, may vary between 3.5 and 7.5%, with different materials requiring somewhat different moisture contents, but in most cases it is preferably in the range A, 5-6.5%. If the moisture content is too low, there are insufficient hydroxyl groups to react with the silane mixture. If the moisture content is too high, the hydrogen chloride residue has too great a chance to form hydrochloric acid. In the case of a cellulosic material, the moisture content of the finished product generally varies between A-7%, so that it is possible to treat the paper as it is and to vary the processing conditions in the processing plant. However, it is preferable to determine the raw material having a moisture content above the treatment area and then pre-dry it in the treatment plant to the level desired for the efficiency of the process and also to ensure uniformity of the moisture content.

In general, the carrier of the silane mixture is air, at which the treatment speed can be between 0.76 and 1.52 m / s with a silane content of 2% and a chamber length of 2.13 m. To increase the speed of the web of material to be treated through the chamber, it is necessary to increase the percentage of silane mixture in the carrier gas . Attempting to raise the concentration in the air to more than 5% will form an explosive mixture. However, this disadvantage can be avoided by adding nitrogen or some other inert gas as a carrier, in which cases the material has been treated even at speeds of 2.54 m / s with a silane content of 20%.

The invention is further illustrated by the following non-limiting examples:

Example I

Kraft paper weighing 11.3 kg per 24 x 36 rice was pre-dried to reduce its moisture content to about 2.5% by weight. The pre-dried paper was then passed as a continuous feed through a chamber fed with vapors from a mixture of 65% by weight methyltrichlorosilane, 20% by weight dimethyldichlorosilane and 15% by weight methyldichlorosilane. The feed rate of silane reagents was 2% by weight of the paper. The paper was passed through the treatment chamber at a speed of 0.25 m / s at a temperature between 32.2-32.8 ° C and an air flow of 1.7 m / h. After the paper was removed from the treatment chamber, it was transferred to a post-drying oven at 135-150 ° C. The tensile strength of the obtained product was 3.89 kg per cm of width, which was practically the same as the tensile strength of the untreated material. The water repellency of the product using the Du Pont drop test was 3.5, which is considered excellent, and its pH was 6.0.

Example II

The procedure of Example I was repeated at a moisture content of 3.95% to give a tensile strength of 3.75 kg / cm 3, a water repellency of 5 and a pH of about 6.0.

6 0 2 6 6 11

Example III

The procedure of Example I was repeated except that the moisture content was 4.4%. The obtained product had a tensile strength of 3.79 kg / cm and a water repellency between 4.5 and 5. Its pH ranged from 5.9 to 6.1.

Example IV

The same basic raw material as in Example I was pre-dried to a moisture content of 4.4%, passed through a chamber fed with the same silane mixture and at the same weight percent rate as in Example I. The temperature in the reaction chamber 3 was 28.3-28.9 ° C and the air flow was 1.7 standard-m / h. The paper was passed through the chamber at a speed of 0.5 m / s to give a product with a tensile strength of 3.21 kg / cm, a water repellency of 4 and a pH of 6.2.

Example V

The procedure of Example IV was followed, except that the web speed was 0.76 m / s, giving a tensile strength of 3.50 kg / cm and a water repellency of 3.5.

Example VI

The procedure of Example IV was repeated except that the web speed was 1.0 m / s to give a tensile strength of 3.73 kg / cm 3, a water repellency of 3.0 and a pH of 6.5.

Example VII

2

Bleached sulphite tissue paper weighing 18.0 g / m 3 was pre-dried to a moisture content of 3.1%. The pre-dried paper was then passed as a continuous feed through a chamber fed with vapors from a mixture of 65% by weight methyltrichlorosilane, 20% by weight dimethyldichlorosilane and 15% by weight methyldichlorosilane. Silane reagents were fed at a weight rate of 2% by weight of the paper and the paper was passed through the chamber at a rate of 0.25 m / s with an air flow into the chamber of 1.7 standard m / h; after removal from the treatment chamber, the paper was taken to a post-drying oven at 135-150 ° C. The tensile strength of the obtained product was 1.14 kg / cm, which was practically the same as the tensile strength of the untreated material.

Its water repellency was 3.5-4.5.

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Example VIII

2

Crepe paper weighing 55.5 g / m was made from Natural Kraft Paper, pre-dried to a moisture content of 4% and passed through a reaction chamber continuously fed with vapors from a mixture of 65% by weight of methyltrichlorosilane, 20% by weight of dimethyldichlorosilane and 15% by weight. methyldichlorosilane. Silane reagents were fed at a weight rate of 6.1% by weight of the paper. The web speed was 1.0 m / s; nitrogen was used as the carrier gas and silane vapors accounted for 20% of the total gas flow. After removal from the treatment chamber, the paper was placed in a freeze-drying oven at 135-150 ° C. The resulting product retained 91.6% of its original tensile strength and had a water repellency of 3-3.5.

Example IX

The procedure of Example VIII was followed, except that the moisture content was 6%, 1.7% by weight of silanes were added and the web speed was 2.0 m / s. The resulting product had a tensile strength of 94.6% of the original and a water repellency of 3.

Example X

The procedure of Example VIII was followed, except that the moisture content was 5%, 1.6% by weight of silanes were added and the web speed was 1.5 m / s. The resulting product had a tensile strength of 87.4% of the original and a water repellency of 3.5-4.

Using the general technique outlined above, the following paper types were considered:

Example XI 2 68.5 g / m bleached kraft paper which retained 90% of its original tensile strength and had a water repellency of 5.

Example XII

2 ...

21.2 g / m carbon paper that retained 75% of its original tensile strength and had a water repellency of 3.5.

Example XIII

13 2 49.0 g / m natural kraft paper mb, which retained 81% of its original tensile strength and had a water repellency of 4-4.5.

Example XIV

Mani1la flag board, which retained 100% of its original tensile strength and had a water repellency of 5.

Example XV

Brown kraft paper which retained 95% of its original tensile strength and had a water repellency of 5.

Example XVI

A blue decorative crepe that retained a vague portion of its original tensile strength and had a water repellency of 4-4.5.

Example XVII

Blue embossed sterilizable wrapping paper that retained 75% of the original tensile strength and had a water repellency of 3-3.5.

It will be appreciated that those skilled in the art, having obtained the information from the foregoing description, may devise numerous other uses and variations and new modes of operation from the specific embodiments described herein without departing from the principle of the invention. Thus, the invention is to be construed as encompassing any and all novel parts and new combinations of parts that exist or are disclosed in the apparatus or technique described herein, and that the invention is limited only by the scope and spirit of the claims.

Claims (8)

A method of rendering a substance water repellent without unacceptable acid decomposition, comprising the steps of: (a) injecting organo-halosilane vapors into a treatment chamber through which the substance passes, and (b) maintaining the vapors in non-laminar conditions under substantially the entire chamber. the length of treatment. Method according to Claim 1, characterized in that the Reynolds number of the vapors exceeds 1000. Process according to Claim 1, characterized in that the Reynolds number of the vapors exceeds 2000. Method according to one of Claims 1 to 3, characterized in that, at a given velocity of the substance, the treatment length gives a residence time of the substance such that additional exposure of the substance to vapors results in a negligible improvement in water repellency. Method according to one of the preceding claims, characterized in that the vapors are removed in the flow direction of the chamber from the lower end by applying a pressure lower than atmospheric pressure. Process according to one of the preceding claims, characterized in that the substance is cellulose-like. Method according to Claim 6, characterized in that the substance is paper. Method according to one of the preceding claims, characterized in that the substance is in the form of a continuous web.