JPH058041B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a method for manufacturing an energy-saving filter, which is improved for the purpose of saving energy and streamlining the production process. (Prior Art) Conventionally, air filters for automobiles, oil filters, fuel filters, etc. have been manufactured by impregnating filter paper with resol type phenol resin (hereinafter abbreviated as resol resin) and volatilizing the solvent.
In the next step, the B-impregnated paper is brought to a dry state, corrugated, and rolled up, and then pleated in the next step, and then C-formed (cured), and then end plates are attached. The characteristics of the cure-type oil filter obtained from resol resin-impregnated paper in the C state are that it has good heat resistance, oil resistance, high bursting strength, and toughness, as well as good air permeability and filtration efficiency. It is. (Problems to be Solved by the Invention) However, the carbonization process of the cure-type oil filter consumes a large amount of heat and time to carbonize the impregnated paper, making it difficult to save energy and streamline productivity. From this point of view, this is a process that should be omitted or improved, and there is a great demand for it. (Means for Solving the Problems) The present inventors have maintained or improved the advantages of conventional filter paper made of resol resin impregnated paper, and also omitted the carbonization step and shortened the carbonization time. Or, as a result of intensive study on a method for manufacturing a filter that can achieve a reduction in C temperature, we have developed a resin composition consisting of a resol resin, a melamine resin, and a curing accelerator, and/or a resin composition consisting of a phenol melamine resin and a curing accelerator. The present invention was completed based on the discovery that by using a resol resin-impregnated paper as an impregnating liquid, the conventionally required carbonization time can be omitted or significantly shortened while maintaining or improving the performance of conventional resol resin-impregnated paper. It came to this. That is, the present invention provides a method for manufacturing a filter, which uses an impregnating liquid containing as a main component a resin composition consisting of a resol resin, a melamine resin, and/or a phenol melamine resin and a curing accelerator. It is. The resol resin used in the present invention includes resins obtained by reacting phenols and aldehydes in the presence of an alkaline catalyst, and which are soluble in methanol. Usually, a calibration curve is created using the molecular weight of polystyrene. The number average molecular weight () measured by gel permeation chromatography (GPC method) is 300 to 1200 (however, free phenol is included in the molecular weight calculation), and the weight average molecular weight () and number average molecular weight () are
Those with a ratio / of 4 to 50 are used, but those with a ratio of / of 500 to 800 and 10 to 35 have good molding processability such as corrugation and pleating, and are free from blocking and cracking. It is preferable. Examples of phenols used as raw materials include compounds such as phenol, m-cresol, p-cresol, o-cresol, 3,5-xylenol, resorcinol, alkylresorcinol, and bisphenol A. From this point of view, phenol is preferred. Examples of aldehydes include compounds such as formaldehyde, paraformaldehyde, trioxane, and acetaldehyde, and among these, formaldehyde is preferred in terms of price/performance ratio. As for the reaction molar ratio of aldehydes and phenols, a range of aldehydes/phenols=(0.7 to 1.6)/1.0 is preferred in terms of good yield and impregnating properties, and no gelation during the reaction. Examples of alkaline catalysts include compounds such as alkali metal hydroxides and carbonates, alkaline earth metal hydroxides and carbonates, alkanolamines, alkylamines, and ammonia. Preferred examples include sodium hydroxide, Examples include potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, and ammonia. The amount used is preferably 5 moles or less per 100 moles of the phenol since the hygroscopicity will not increase. The melamine resin used in the present invention is produced by conducting an addition reaction between a melamine compound and an aldehyde in the presence of an alkaline catalyst, then adding an acid and an alcohol, making it weakly acidic or acidic, and proceeding with an addition condensation reaction to form a polymer. Examples include resins obtained by etherifying some or all of the alkoxy groups such as methylol groups produced with the alcohol, and which are soluble in methanol.
Among these, those in which aldehydes and melamine compounds are reacted at a molar ratio of (2.0 to 5.0)/1.0 are preferred because they have excellent reactivity and solubility in methanol. The melamine compound used here has the general formula (However, R ₁ to R ₆ in the formula are hydrogen atoms, -OH, -
_{CH2OCH3 , -CH2OC2H5 , -CH2OH , -CH2CH2 _}
OH, -CH ₂ CH ₂ CH ₂ OH. However, R ₁ ~
At least one of R ₆ is a hydrogen atom. ) and compounds obtained by modifying the compound of general formula (1) with known modifying compounds such as urea, dicyandiamide, benzoguanamine, and acetoguanamine. The aldehydes and alkaline catalyst used here are the same as those used in the production of the resol resin. Examples of acids include mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid;
Organic acids such as oxalic acid, maleic acid, and formic acid can be used, but it is preferable that a methanol-soluble salt is produced by a neutralization reaction with an alkaline catalyst because filtration becomes unnecessary. In this case, it is preferable to use as little amount of alkaline catalyst as possible in order to prevent moisture absorption due to residual salt. Alcohols include methanol, ethanol, n-propanol, isopropanol, n-
Examples include aliphatic alcohols such as butanol and isobutanol, and methanol is particularly preferred because it has a high drying temperature and is inexpensive. The blending ratio of resol resin and melamine resin is usually in the range of 95/5 to 30/70 (resin solid weight ratio), but especially 90/70.
When blended in the range of 10 to 60/40, the resin solid content
Even when diluted with methanol to an impregnating concentration of 40% by weight or less, no insoluble matter is generated, and the viscosity at the impregnating concentration is within the range suitable for impregnation (100% by weight with a resin solid content of 30% by weight).
centipoise or less), the curing speed is sufficiently fast, the resulting B-cured paper has high rigidity, and it does not sag, so it is preferable. The phenol melamine resin used in the present invention includes the same phenols, aldehydes, and melamine compounds of general formula (1) as described above (however,
Examples include co-condensates containing as essential raw materials (including modified melamine compounds such as those described above). Since this phenol melamine resin is a terpolymer, there are various ways to manufacture it, including the order in which raw materials are added, and there are no particular limitations, but as an example, after making an addition reaction between a melamine compound and an aldehyde using an alkaline catalyst, Alcohol, acid, and the above-mentioned resol resin, preferably = 500 ~
Add resol resin of 800, / = 10 to 35,
There is a method of proceeding with etherification of an alkoxy group with alcohol and co-condensation with a resol resin. The reaction molar ratio of phenols, melamine compounds, and aldehydes is phenols/melamine compounds/aldehydes = 1.0/(0.03~
The range of 0.3)/(1.0 to 1.9) is preferable because the curing speed and dilutability with methanol are high and the odor of aldehydes is low. In addition, in the present invention, a mixture of resol resin and melamine resin and/or phenol melamine resin is used, but when comparing the mixture and phenol melamine resin, the blending ratio of phenol resin and melamine resin can be selected as appropriate, and the filter C-treated paper It is preferable to use a mixture of a resol resin and a melamine resin because the heat resistance and curability of the resin can be freely adjusted and the storage stability of the resin itself is superior to that of a phenol melamine resin. The curing accelerator used in the present invention may be any compound that lowers the pH of the impregnation-curing system to a region lower than 7, and is not particularly limited. For example, hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, formic acid, para-toluenesulfonic acid , xylene sulfonic acid, maleic acid, inorganic or organic acidic compounds such as phosphoric acid ester compounds; ammonium hydrochloride, ammonium sulfamate,
Examples include salts of acid and amine compounds, so-called "latent catalysts", such as monoethanolamine salts of hydrochloric acid. Among these, phosphoric acid and phosphate ester compounds are preferred because they dissolve well in methanol, are highly effective even in small amounts, and have low corrosivity. The amount of curing accelerator to be added varies widely depending on the type of curing accelerator, and is difficult to specify, but for example, when using an acidic compound, the pH of a methanol solution with a resin solid content of 10% by weight is It is usual to add it so that the pH is 7 or less, and it is especially preferable to add it so that the pH is 1 to 5 because a sufficiently fast curing speed can be obtained. In addition, when a "latent catalyst" is used, the range corresponds to the amount that results in the above PH when the acidic compound (hydrochloric acid in terms of ammonium hydrochloride) used in the catalyst is used alone. As the filter paper used in the method of the present invention, any conventionally known filter paper is preferably used. For example, there is general-use filter paper that is mainly made of linter pulp fibers, with synthetic fibers such as rayon and polyester added as needed, and paper is made to adjust air permeability, basis weight, thickness, etc. The impregnation of the obtained impregnating liquid into the filter paper is as follows:
The so-called dip-squeeze method uses an impregnating solution with a resin solid content of 5 to 20% by weight and impregnation by dipping and squeezing operations, and the resin solid content
A resin solid content of 15 to 30 parts by weight is attached to 100 parts by weight of filter paper by a conventionally known method such as the Kiss-coat method in which 20 to 40% by weight of impregnating liquid is used for impregnation with a kiss roll. It is generally carried out as follows. B-drying of impregnated paper is carried out under normal drying conditions, e.g.
It is carried out at 80 to 120℃ for 1 to 10 minutes, and is rolled up after corrugating. The filter B paper thus wound is subjected to a pleating process using a pleating machine. This filter B conversion paper is used for oil filters.
When applied, since the operating environment is as high as 80 to 150℃, it is possible to omit the C conversion and use pleated filter B conversion paper and assemble it into the filter element. Also good. The temperature of the C conversion process is 100 to 200℃, and the time is 10 seconds to 30 seconds.
The C conversion is carried out at a lower temperature or in a shorter time than when using only conventional resol resins. Of course, if the temperature is low, it will take a long time, and if the temperature is high, it will take a short time. Comparing the optimum conditions (conditions where the bursting strength is maximized) for C conversion at the same temperature, for example, the B conversion paper used in the present invention has a
It takes 10 seconds to 6 minutes, but in the case of conventional resol resin only, it takes 8 to 15 minutes at the same temperature. After converting into carbon, it is cut to an appropriate length and assembled as a filter element. (Effects of the invention) According to the filter manufacturing method of the present invention, while maintaining the performance of conventional resol resin-impregnated paper,
Alternatively, while improving the carbonization time required by conventional impregnated paper, it can be omitted or significantly shortened, or it can be converted to carbon in the same time even at a lower temperature than before, streamlining the process related to carbonization or saving energy. There is. (Examples) Next, the present invention will be specifically explained with reference to Examples, Comparative Examples, and Production Examples, and all parts and percentages in the Examples are based on weight unless otherwise specified. Production Example 1 (Production of resol resin) A reflux condenser, a thermometer,
A stirrer was set, and 887 g of phenol, 913 g of 37% formalin, and 8.3 g of 96% KOH were charged, and after reacting at reflux temperature for 5 hours, vacuum distillation was performed at 50 to 70°C to concentrate. When almost no distillate comes out, stop vacuum distillation and maintain the temperature at 70°C. During this time, the reaction solution in the flask was sampled, diluted with methanol to make the resin solid content 50%, the viscosity was measured, and when the viscosity reached 150 centipoise, methanol was gradually added to the flask, and the reaction solution inside was While sufficiently dissolving the resin, the resin solid content was adjusted to 50% to obtain a resol resin (A-1). When the number average molecular weight () and weight average molecular weight () of this resin were measured using the GPC method, it was found that
620, / was 20. Production Example 2 (Production of melamine resin) A reflux condenser, a thermometer,
A stirrer was set, and 307 g of melamine, 687 g of 37% formalin, and 2 g of 96% KOH were charged, the temperature was raised to 60°C, and the methylolation reaction was continued at 60°C until crystals precipitated. Next, vacuum distillation was continued at 50°C until stirring became difficult, then 1170g of methanol and 2.6g of 85% formic acid were added, and after etherification reaction was carried out at 50°C for 30 minutes, 0.8g of 96% KOH was added. The system was then neutralized, and excess methanol was removed by vacuum distillation to obtain a melamine resin (B-1) with a resin solid content of 80%. Production Example 3 (Production of phenol melamine resin) A reflux condenser, a thermometer,
A stirrer was set, and 97 g of melamine, 217 g of 37% formalin, and 0.63 g of 96% KOH were charged, the temperature was raised to 60°C, and the methylolation reaction was continued until crystals precipitated. Next, vacuum distillation was performed at 50°C, and after confirming that no distillate was distilled out, 370 g of methanol and the resol resin (A
-1) 1242g was added. Furthermore, 5.9 g of 85% formic acid was added and the methylolated melamine resin was subjected to a methyl etherification reaction with methanol and a cocondensation reaction with the phenol resin at 50°C for 30 minutes.
The system was neutralized with 0.3 g of KOH, and excess methanol was removed by vacuum distillation to obtain a phenolmelamine resin (C) with a resin solid content of 50%. Production Example 4 (Production of resol resin) Using 787 g of phenol, 1013 g of 37% formalin, and 16.3 g of 48% NaOH, the same operation as in Production Example 1 was carried out except that the reaction was carried out at reflux temperature for 4 hours, and the resin solid content was When the viscosity of 50% is 200 centipoise, methanol is added to reduce the resin solid content to 50 centipoise.
% to obtain a resol resin (A-2). This resin had a weight of 750 and a weight of 30. Production Example 5 (Production of resol resin) Using 1068 g of phenol, 733 g of 37% formalin, and 17.2 g of potassium carbonate, the same operation as in Production Example 1 was carried out except that the reaction was carried out at reflux temperature for 4 hours, and the resin solid content was 50 When the viscosity of % reaches 100 centipoise, methanol is added to reduce the resin solids content to 50 centipoise.
% to obtain resol resin (A-3). This resin had a rating of 550 and a rating of 15. Production example 6 Melamine 256g, 38% formalin 737g and 96
%KOH 1.7g, then etherification using 1320g methanol and 85% formic acid 2.2g, and neutralization using 0.7g 96% KOH. A melamine resin (B-2) having a resin solid content of 80% was obtained. Production example 7 Melamine 384g, 37% formalin 615g and 96
%KOH 2.5g, then etherification using 1360g methanol and 85% formic acid 3.3g, and neutralization using 96% KOH 1.1g. A melamine resin (B-3) with a resin solid content of 80% was obtained. Examples 1 to 6 A filter paper mainly made of cotton linter pulp with a basis weight of 140 g/m ² and a thickness of 0.6 mm was used as the test paper, and on the other hand, the resol resins (A-1) of Production Examples 1 to 7 of the previous period were used. (A-3), melamine resin (B-1) to (B-3), phenol melamine resin (C), Betsukamine P198 [Dainippon Ink & Chemicals
Co., Ltd. phosphate ester curing accelerator], maleic anhydride, and methanol to a resin solid content of 10%.
% of the composition shown in Table 1 to obtain an impregnating liquid, and a test paper was impregnated with this by a deep squeeze method to obtain an impregnated paper. Next, each impregnated paper was solvent dried at 80°C for 5 minutes (B
The paper was dried at 150°C for 3 minutes under heat curing (C) conditions, and the resulting filter C paper was subjected to a bursting strength test, and good results were obtained. It was done. Table 1 shows the results.
Shown below. Note that the bursting strength test was measured in accordance with JIS P-8112. Note that the mixture of resol resin and melamine resin before adding Betsukamine P198 (curing accelerator) had better storage stability than the phenol melamine resin. Comparative Example 1 A filter C-treated paper for comparison was obtained in the same manner as in Example 1 except that no curing accelerator was added. A similar test was then conducted and the results shown in Table 1 were obtained. This C paper had the same bursting strength as the B paper under the C conversion conditions of 150° C. for 3 minutes, and its strength had not increased. Comparative Example 2 A filter C-treated paper for comparison was obtained in the same manner as in Comparative Example 1 except that only resol resin (A) was used as the impregnating resin. Then a similar test was carried out,
The results shown in Table 1 were obtained. This C paper had the same bursting strength as the B paper under the C conversion conditions of 150° C. for 3 minutes, and its strength had not increased. Comparative Example 3 A filter C-treated paper for comparison was obtained in the same manner as in Example 1 except that the use of melamine resin (B) was omitted. Although the bursting strength of this C paper showed a slight rise compared to that of the B paper, it was not sufficient and was inferior.

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Claims (1)

[Claims] 1 resol type phenolic resin and melamine resin,
and/or a method for manufacturing a filter, characterized in that an impregnating liquid containing as a main component a resin composition consisting of a phenol melamine resin and a curing accelerator is used.