JPH069253A - Sealant composition and its production - Google Patents

Abstract

PURPOSE:To readily produce a sealant composition excellent in strength, compression recovery and thermal resistance and free from asbestos pollution by simultaneously beating a fibrillated aromatic polyamide fiber and organic fiber and subsequently blending an inorganic binder, etc., therewith. CONSTITUTION:An aromatic polyamide fiber and an organic fiber (e.g. cellulose pulp or hemp) are beaten so as to be fibrillated. The resultant fibrillated fibers, together with an inorganic heat-resistant fiber (e.g. glass fiber or rock wool) are opened. Inorganic particles and an organic binder (e.g. a modified acrylic acid ester copolymer) are then admixed therewith in order. An inorganic cationic flocculant and an acrylamide-based polymer flocculant are further added thereto in order and the resultant mixture is then subjected to the wet method paper- making and subsequently to dehydration press. The inorganic heat-resistant fiber is bonded between small massive flocs composed of the fibrillated aromatic polyamide fiber and the organic fiber by using an organic binder so that the inorganic heat-resistant fibers may three-dimensionally exist and that the inorganic particles may be uniformly dispersed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant sealant composition used in automobiles, chemical industries, water heaters, heaters, various equipment and the like, and a method for producing the same.

[0002]

2. Description of the Related Art So-called asbestos joint sheets, asbestos beater sheets, asbestos paper, asbestos foams, etc. have been widely used as conventional sealing materials. These sheets contain asbestos, which is an inexpensive natural mineral fiber, in a proportion of 60 to 95 wt%, and have no functional problems in terms of sealing properties, heat resistance, chemical resistance, etc. It was also extremely excellent in terms of. However, asbestos fibers are scattered not only from the step of producing the sheet but also from the equipment used, which may cause health problems, and the problem of asbestos pollution has been greatly highlighted. Therefore,
Researches for producing beater sheets and joint sheets using asbestos substitute fiber base materials have been actively conducted.

As an asbestos alternative fiber, glass fiber,
Carbon fiber, potassium titanate fiber, sepiolite,
Attempts have been made to manufacture a sheet-like material by using inorganic fibers such as silica-alumina fibers and stainless fibers, or organic fibers such as aromatic polyamide fibers, novoloid fibers and polyethylene fibers. By the way, potassium titanate fibers, sepiolite, etc. have a short fiber length and a low aspect ratio, so these fibers alone or in combination are made into a sheet-like material, and when a sealing material is formed, compared with a sealing material using asbestos, it is compressed. There is a problem that the restoration rate and the strength are extremely poor. Further, when glass fibers, inorganic fibers such as silica-alumina fibers are used alone or in combination to form a sheet, and a sealing material is formed, in order to obtain a high bulk density for the purpose of providing airtightness, high-pressure pressing is performed, At the points of contact or intersection of the base fibers, the base fibers are crushed and the aspect ratio of the fibers is lowered, resulting in a problem that the compression recovery rate and strength of the obtained sealing material are significantly inferior. On the other hand, carbon fibers and organic fibers such as aromatic polyamide fibers, novoloid fibers, and polyethylene fibers deteriorate in the characteristics of the fibers from around 100 to 200 ° C, and are completely carbonized or burned off at 400 ° C or higher. As a sealing material in 100-200
It was difficult to use in the temperature range above ℃. Furthermore, in the case of using any of the above fibers, the conventional method for producing a joint sheet, that is, the fibers disintegrated and dusted by the disintegrator, the rubber base dissolved in the solvent and the rubber chemicals are stirred by a stirrer. Clay-like joint seams that are well mixed
The following problems have been encountered in the method of producing a raw material and plate-making the raw material with a heat roll and a cooling roll.

That is, it is difficult to uniformly disperse and knead the inorganic or organic fibers in a rubber base as a binder in the step of manufacturing the joint sheet. In addition, when the raw material of the joint sheet is heated and rolled by a heat roll and a cooling roll to be attached to the heat roll in a sheet form, the raw material may be attached to the cooling roll, resulting in poor workability and wrinkles on the joint sheet. However, problems such as occurrence of irregularities, remarkable unevenness of thickness, and impossibility of sheet formation occurred. It was studied to add an antistatic agent such as a surfactant at the time of mixing the raw materials for the joint sheet to solve the problem that the raw materials for the joint sheet as described above adhere to the cooling roll. It cannot be said that it is suitable in terms of cost and the like, and the problem has not been solved yet. On the other hand, using any of the above fibers, a beater sheet-like material manufacturing method such as a papermaking press by mixing the raw materials in water has been devised, but the base fiber is crushed at the time of pressing and the aspect ratio of the fiber is However, there is a problem in that the strength and the compression recovery rate of the obtained sealing material are significantly deteriorated. Further, a method of wet mixing at a predetermined ratio has been attempted in order to utilize the advantages of each of the inorganic fiber and the organic fiber, but it is difficult to uniformly disperse and mix them, and none of them has been put to practical use.

Therefore, the present invention aims to eliminate and solve the above-mentioned drawbacks of the prior art, and as a result of various studies to achieve this objective, as a result, a seal which is low in cost and excellent in strength and compression resistance is obtained. The present invention has been completed by newly discovering a material composition and a manufacturing method thereof.

[0006]

[Means and Actions for Solving Problems] The present invention provides a sealant composition containing an inorganic heat resistant fiber having an average fiber length of 10 mm or less, an aromatic polyamide fiber, an organic fiber, inorganic particles and an organic binder as main components. In the product, the aromatic polyamide fiber and the organic fiber are fibrillated to form a blob of flocs, and the inorganic heat-resistant fiber is three-dimensionally present by being bound by an organic binder between the flocs of the blob. However, the inorganic particles are uniformly dispersed in the sealant composition and have a density of 0.
A sealing material composition and a method for producing the same are characterized in that they are 7 to 1.3 g / cm ³ .

The present invention will be described in detail below. The sealant composition of the present invention has the following properties in order to ensure strength and compression recovery.
It is necessary to use fibrillated aromatic polyamide fibers. The reason is that the aromatic polyamide fiber has a high strength as a simple substance, but the tensile strength and the delamination strength are lowered because the fiber surface is smooth. From this, by fibrillating the surface of the fibers so that the fibers are entangled with each other, the desired tensile strength and delamination strength are obtained after forming the sheet.

Examples of the fibrillated aromatic polyamide fibers include Kevlar as a trade name and wet pulp (manufactured by DuPont). According to the present invention, the compounding ratio of the fibrillated aromatic polyamide fiber and the organic fiber is in the range of 0.1 to 20 parts by weight of organic fiber to 1 part by weight of fibrillated aromatic polyamide fiber. It is preferable. The reason is that when the amount of the organic fibers is less than 0.1 parts by weight, the fibrillated aromatic polyamide fibers are entangled with each other to form a long tail, while when the amount of the organic fibers is more than 20 parts by weight, the sealing material is large. It is not possible to obtain the strength and compression recovery property as described above, and the heat resistance is significantly deteriorated. Cellulose pulp, hemp, polyester, and the like can be used as the organic fiber, and among these, cellulosic pulp is preferable in terms of fiber length and cost.

According to the present invention, it is preferable that the ratio of the aromatic polyamide fiber fibrillated by simultaneous beating and the organic fiber in the sealant composition is 3 to 30 wt%. The reason is that the fibrillated aromatic polyamide fiber and the organic fiber account for 3 w in the sealant composition.
This is because if it is less than t%, the strength and compression recoverability as a sealing material cannot be obtained, while if it is more than 30 wt%, the cost becomes high and the heat resistance becomes poor.

According to the present invention, it is necessary that the inorganic heat resistant fiber is 40 to 80 wt% in the sealant composition. The reason is that if it is less than 40 wt%, the heat resistance is deteriorated, and if it is more than 80 wt%, the fibers are broken at the contact points between the fibers during press molding and the strength is reduced. As the inorganic heat resistant fiber,
It can be used depending on the application of the sealing material on which silica-alumina fiber, glass fiber, rock wool, etc. are formed.

The inorganic heat resistant fiber has an average fiber length of 10
It must be less than or equal to mm. The reason is that if the average fiber length is longer than 10 mm, the fibers are two-dimensionally arranged perpendicularly to the pressing direction when press-molded into a sheet, and the restorability of the sheet deteriorates. If the average fiber length is too short, the heat resistance of the sheet deteriorates, so it is preferably 1 mm or more, and particularly preferably in the range of 2 to 7 mm.

According to the present invention, the organic binder is advantageously less than 10 wt% in the sealant composition.
The reason is that the organic binder has its strength increased by the heat crosslinking described later, but when it is 10 wt% or more, the heat resistance is significantly deteriorated. According to the present invention, it is advantageous to use NBR, SBR, modified acrylic acid ester copolymer or the like as the organic binder.

In addition to the above main components, an inorganic binder or an inorganic filler may be added, if necessary, in order to maintain heat resistance and strength. As the inorganic binder or the inorganic filler, sepiolite, talc, clay, synthetic mica or the like can be used, and among them, sepiolite is more advantageous as the heat resistant binder. In addition, in order to maintain the strength of the sealant composition during actual use, it is advantageous to include an inorganic colloid in the sealant composition. As the inorganic colloid, commercially available silica sol, alumina sol and the like can be used.

In the sealant composition of the present invention, it is necessary that the inorganic heat-resistant fibers are three-dimensionally present by being bound by the organic binder between the flocs of the aromatic polyamide fibers and the organic fibers in the form of small blocks. is there. The reason is that the presence of the inorganic heat-resistant fiber in three dimensions makes it possible to maintain good restorability of the sheet during actual use.

In the sealing material composition of the present invention, it is necessary that the inorganic particles are uniformly dispersed and present in the sealing material composition. The reason is that since the inorganic particles are uniformly dispersed in the sealing material composition, a sealing material having a high density can be obtained with a relatively low press molding pressure, and the sealing performance with few pores is excellent. This is because a sealing material composition can be obtained.

Next, the method for producing the sealing material composition will be described in detail in order. According to the present invention, the aromatic polyamide fiber and the organic fiber need to be fibrillated by simultaneous beating treatment. The reason is that when the fibrillated aromatic polyamide fibers are used as they are as a gasket composition and subjected to wet stirring, the fibers are entangled with each other to form long tails and the dispersibility is significantly deteriorated.

In order to prevent the long tail, a filler or the like is added and the filler is filled between the fibers of the fibrillated portion, but in the case of a granular or scale-like filler, It is effective when the fibrillated part is short, but when the fibrillated part is long,
It is insufficient to prevent long tails. Therefore, organic fibers having an aspect ratio to some extent are effective, and long tails are prevented by blending the fibrillated aromatic polyamide fibers with organic fibers and simultaneously beating.

The beating degree of the simultaneous beating is 200 to 40.
It is advantageous to set the range to 0 ml (Canadian Freeness type beating machine). The reason is 400 ml
If it is larger than this, the fibrillated polyamide fiber and the organic fiber are not sufficiently mixed, while if it is smaller than 200 ml, the drainage is remarkably lowered and the productivity is extremely deteriorated. Then, the inorganic heat-resistant fiber and the organic binder and the inorganic binder or the inorganic filler, if necessary, are added to and mixed with the aromatic polyamide fiber and the organic fiber that are simultaneously beaten and fibrillated. The composition is preferably mixed by a wet method, and then it is preferable that the composition is densified by dehydration pressing after papermaking.

Further, after the paper is formed, it may be dehydrated and dried, and then hot-pressed in order to impart airtightness as a sheet material and to heat-crosslink the organic binder to obtain strength. The temperature for performing the hot pressing is preferably 60 ° C. to 300 ° C., and the pressing pressure is preferably 5 to 200 kg / cm ² . The reason is that it is difficult to crosslink the organic binder in a short time when the pressing temperature is lower than 60 ° C., and when the pressing temperature is higher than 300 ° C., the organic binder is modified and strength is not obtained. In addition, the pressure of the hot press is 5 to 200 kg / cm ²
The reason why it is preferable to be 5% / cm ² is that the bulk density as a sheet material does not increase. On the other hand, 20
This is because if it is higher than 0 kg / cm ² , the inorganic fibers in the composition will be broken, resulting in a decrease in strength.

The sealing material and the manufacturing method thereof according to the present invention have the following effects. First, since a fibrillated aromatic polyamide fiber having high strength and high elasticity is used, it has excellent strength as a sealing material and excellent compression recovery rate. Further, the fibrillated aromatic polyamide fiber is beaten simultaneously with an organic fiber. Therefore, a product with excellent strength can be obtained without forming a long tail or the like. In addition, since it contains inorganic heat resistant fibers, it has excellent heat resistance, and it is possible to maintain the recovery rate even after heating. Furthermore, by performing hot pressing, the inorganic heat resistant fibers do not break and the sealability is high. A dense sealing material composition is obtained. The present invention will be described with reference to examples.

[0021]

【Example】

(Example 1) Commercially available Kevlar wet pulp and cellulose pulp were beaten in equal weights using a Jones-Bertram special beater so that the beating degree was 300 ml. Next, in a pulper, the Kevlar wet pulp 2.5 wt%, the cellulose pulp 2.5 wt%, the shattered rock wool 59 wt% as the inorganic heat resistant fiber, and the sepiolite 25 wt% as the inorganic binder in the dry solid content weight ratio.
%, NBR latex 2.5 wt% and silica sol 5
After stirring and mixing wt% as a slurry having a concentration of about 1 wt%, 2 wt% of a sulfuric acid band was added, then 1 wt% of low molecular weight polyacrylic amide was added, and a polymer flocculant was further added to cause aggregation, Thickness of 10 with papermaking mold
mm wet sheet was produced. Then, the wet sheet was dehydrated and pressed by a hydraulic press to have a thickness of 3 mm, and then dried at 110 ° C. for 5 hours. In addition, after cutting the obtained sheet into a 20 mm square, it was sandwiched between SUS304 metal plates and compressed by 20% with bolts and nuts (thickness 3.0.
mm is fixed at 2.4 mm), and then fixed in an electric furnace at 275 ° C x
After the heat treatment for 24 hours, the restoration ratio (%) was measured and found to be 65%. The restoration rate was calculated by the following formula. Recovery rate (%) = (T ₂ −T ₁ ) × 100 / (To −
T ₁ ) Here, To is the initial sample thickness, T _{1 is} the sample thickness after 20% compression, and T ₂ is the sample thickness when released from the fixing jig after the heat treatment. Then, the sealing material was punched into a donut shape and used as a gasket in a vaporizing cylinder of a commercially available petroleum F / F fan heater. As a result of performing 100 cycles of firing for 10 hours and stopping for 2 hours as one cycle. There was no fuel leak or exhaust gas leak.

(Example 2) Commercially available Kevlar wet pulp and cellulose pulp in equal weights were used in Jones-Be.
It was beaten using a rtram special beater so that the beating degree was 300 ml. Next, in a pulper, 10 wt% of the Kevlar wet pulp, 10 wt% of the cellulose pulp, 65 wt% of shredded rock wool as an inorganic heat resistant fiber, 10 wt% of sepiolite as an inorganic binder, and 5 wt% of NBR latex in a dry solid weight ratio. After stirring and mixing as a slurry having a concentration of about 1 wt%, a wet sheet having a thickness of 10 mm was made into paper by a paper making die. Then, the wet sheet was dehydrated and pressed by a hydraulic press to have a thickness of 3 mm, and then dried at 110 ° C. for 5 hours. Furthermore, the dry sheet was placed at 160 ° C. × 120 kg / cm ²
Hot press for 5 minutes, thickness 2.5 mm, bulk density 1.
A sheet of 4 g / cm ³ was obtained. In addition, after cutting the obtained sheet into a 20 mm square, it was sandwiched between SUS304 metal plates and compressed by 10% with bolts and nuts (thickness: 2.5 mm
(2.25 mm), and then fixed in an electric furnace at 275 ° C x 2
After heat treatment for 4 hours, the restoration rate (%) was measured and found to be 7
It was 3%.

(Comparative Example 1) The same as in Example 1, but without simultaneously beating the Kevlar wet pulp and the cellulose pulp, a sheet was prepared in the same manner as described below, and a restoration ratio (%) was obtained in the same manner as in Example. ) Was 42%.
As a result of using the F / F fan heater as in the example, 2
Exhaust gas leaked out in the 5th cycle.

(Comparative Example 2) The same as Example 2, but
When the hot pressing temperature was 200 ° C., the emulsion latex was significantly discolored during the hot pressing, and the elasticity of the sheet was lost.

(Comparative Example 3) The same as in Example 1, except that 20% by weight of Kevlar wet pulp and 2 of cellulose pulp were used.
A sheet having 5 wt%, 35 wt% silica-alumina fiber as the inorganic heat-resistant fiber, 10 wt% talc as the inorganic filler, and 10 wt% emulsion latex (NBR) was manufactured, and the restoration rate (%) was measured to be 28%. When the F / F fan heater was used as in Example 1, fuel leaked out at the 5th cycle.

[0026]

As described above, the present invention uses fibrillated aromatic polyamide fibers having high strength and high elasticity,
Moreover, by beating with organic fibers at the same time and then mixing an inorganic binder and an inorganic heat resistant fiber, it has excellent strength and compression recovery properties, and because it contains an inorganic heat resistant fiber, it has excellent heat resistance and there is no concern about the occurrence of pollution at low cost. The sealant composition can be obtained, and the effect of industrial contribution is extremely large.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C04B 32/00 A

Claims (5)

[Claims] 1. A sealant composition comprising an inorganic heat-resistant fiber having an average fiber length of 10 mm or less, an aromatic polyamide fiber, an organic fiber, inorganic particles and an organic binder as a main component, wherein the aromatic polyamide fiber and the organic fiber. Are fibrillated to form a small floc, the inorganic heat-resistant fiber is three-dimensionally present by being bound by an organic binder between the small flocs, the inorganic particles in the sealant composition. A sealing material composition which is present in a uniformly dispersed state and has a density of 0.7 to 1.3 g / cm ³ . 2. The sealing material composition according to claim 1, wherein the ratio of the aromatic polyamide fiber to the organic fiber is in the range of 0.1 to 20 parts by weight with respect to 1 part by weight of the aromatic polyamide fiber. 3. The aromatic polyamide fiber and the organic fiber are 3
~ 30 wt%, 40-80 wt% of the inorganic heat resistant fiber
%, The organic binder is contained in an amount of less than 10 wt%, The sealing material composition according to claim 1. 4. A fibrillated aromatic polyamide fiber, an organic fiber and an inorganic heat resistant fiber are defibrated by simultaneous beating treatment, and then inorganic particles and an organic binder are sequentially added and mixed, and further an inorganic cation coagulant and an acrylic are added. Wet papermaking after sequentially adding amide polymer flocculant,
A method for producing a sealing material composition, which comprises dewatering and pressing. 5. The beating degree of the aromatic polyamide fiber fibrillated by the simultaneous beating treatment and the organic fiber is 2
The method for producing a sealing material composition according to claim 4, wherein the amount is in the range of 00 to 400 ml.