JP2010013610A - Phenol resin composition for frictional material and thermosetting phenol resin composition for frictional material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phenol resin composition and a thermosetting phenol resin composition, improved in flame retardance, without greatly damaging the mechanical characteristic of a frictional material. <P>SOLUTION: The phenol resin composition for the frictional material and the thermosetting phenol resin composition for the frictional material are characterized by containing (a) a novolac type phenol resin having a 70 to 130°C resin-softening point and (b) a triazine compound obtained by reacting at least one compound selected from the group consisting of melamine, melamine cyanurate, guanamine, adipoguanamine, benzoguanamine, acetoguanamine, succinoguanamine, melam, melem and melon with an aldehyde, and having a nitrogen content of 4 to 30 wt.%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a phenol resin composition for a friction material and a thermosetting phenol resin composition for a friction material.

Phenolic resins have excellent heat resistance and adhesiveness with inorganic fillers, and are widely used as binders for friction materials such as brakes. In this application, a powdery thermosetting phenolic resin composition obtained by pulverizing and mixing a random novolak type phenolic resin and hexamethylenetetramine is widely used.
As a manufacturing process of a friction material such as a brake, the thermosetting phenol resin composition is used as a binder, and a fibrous inorganic filler base material such as glass fiber, aramid fiber or metal fiber, calcium carbonate, barium sulfate. Examples include a method of obtaining a molded body by subjecting a mixture of a powdery inorganic filler base material such as a mixture of cashew dust and the like to heat and pressure molding using a hot press machine.
The characteristics required for the resin for friction materials from before are heat resistance, wear resistance, high friction coefficient, low noise, low moisture absorption, vibration absorption, and the like. In order to satisfy such required characteristics, various techniques relating to a phenol resin composition for a friction material have been disclosed.
In recent years, instead of metal fibers, friction materials using aramid fibers and the like that can realize a high friction coefficient, rotor aggression, low noise, vibration absorption, etc. in a high balance have become mainstream. On the other hand, due to the increase in organic components, heat resistance, especially flame retardancy, is inferior compared to previous metal fiber blends, and new problems such as smoke generation and combustion of friction materials under high-load operating conditions have also occurred. Improvement is desired.
Examples of a general method for making a resin flame-retardant include a method of adding a phosphorus-containing substance and a nitrogen-containing substance (for example, Patent Document 1 and Patent Document 2). Of these, most nitrogen-containing substances are basic substances, and there is an advantage that when a friction material is used, the generation of rust on the rotor can be suppressed. However, in order to obtain a sufficient flame retarding effect using only a nitrogen-containing substance, it is necessary to add a large amount, and there is a problem that the mechanical strength is reduced when a friction material is used.

JP 2000-234091 A WO2006 / 043460

  According to the present invention, a phenol resin composition and a thermosetting phenol resin composition having improved flame retardancy are provided without impairing the mechanical properties of the friction material.

Such an object is achieved by the following present inventions (1) to (4).
(1) A novolak type phenol resin (a) having a resin softening point of 70 to 130 ° C., and melamine, melamine cyanurate, guanamine, adipoguanamine, benzoguanamine, acetoguanamine, succinoguanamine, melam, melem and melon A friction material comprising a triazine compound (b) obtained by reacting an aldehyde with at least one selected from the group, and having a nitrogen content of 4 to 30% by weight of the total resin composition Phenolic resin composition.
(2) The phenol resin composition for a friction material according to (1), wherein the triazine compound (b) includes a methylol group, a methylol ether group, and a dimethylene ether group.
(3) The phenol resin composition for a friction material according to item (1), wherein the triazine compound (b) includes a compound modified with phenols.
(4) A thermosetting phenol resin composition for a friction material, comprising hexamethylenetetramine as a curing agent in the phenol resin composition for a friction material according to any one of items (1) to (3).

  According to the present invention, a phenol resin composition and a thermosetting phenol resin composition having improved flame retardancy can be obtained without greatly impairing the friction material mechanical properties. The obtained phenol resin composition and thermosetting phenol resin composition can be suitably used particularly for various friction materials.

  Below, the phenol resin composition for friction materials and the thermosetting phenol resin composition for friction materials of this invention are demonstrated. The phenol resin composition for a friction material of the present invention comprises a novolac type phenol resin having a resin softening point of 70 to 130 ° C. and a triazine compound, and has a nitrogen content of 4 to 30% by weight. Moreover, it is the thermosetting phenol resin composition for friction materials which contains hexamethylenetetramine as a hardening | curing agent.

  First, the phenol resin composition for a friction material of the present invention will be described. As a novolak type phenol resin (a) used for this invention, the resin softening point is 70-130 degreeC, Preferably it is 80-125 degreeC. Thereby, favorable mechanical strength can be obtained as a phenol resin composition for a friction material. When it is less than the lower limit value of the resin softening point, blocking of the phenol resin composition for a friction material may be induced, causing uneven distribution of the resin when used in the friction material, and reducing mechanical strength. Moreover, when higher than an upper limit, fluidity | liquidity is insufficient at the time of friction material shaping | molding, and it may cause a mechanical strength fall.

  The structure of the novolac type phenol resin (a) is not particularly limited. For example, the phenol novolac resin, the cresol novolac resin, the resorcin novolac resin, the xylenol novolac resin, the alkylphenol novolac resin, the naphthol novolac resin, Bisphenol A novolak type resin, phenol aralkyl novolak type resin, phenol diphenyl aralkyl novolak type resin, phenol naphthalene novolak type resin, phenol dicyclopentadiene novolak type resin, and novolak type modification with cashew nut oil, terpene, tall oil, rosin, rubber, etc. A phenol resin etc. are mentioned. These can be used alone or in combination of two or more.

  Although it does not specifically limit as phenols used as a raw material of the said novolak-type phenol resin (a), For example, cresol, such as phenol, o-cresol, m-cresol, p-cresol, 2, 3- xylenol, 2, 4 -Xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, xylenol such as 3,5-xylenol, ethylphenol such as o-ethylphenol, m-ethylphenol, p-ethylphenol, isopropyl Butylphenols such as phenol, butylphenol and p-tert-butylphenol, alkylphenols such as p-tert-amylphenol, p-octylphenol, p-nonylphenol and p-cumylphenol, p-phenylphenol and aminopheno Monohydric phenol substituents such as nitrophenol, dinitrophenol, trinitrophenol, cardanol, and monohydric phenols such as 1-naphthol and 2-naphthol, resorcin, alkylresorcin, pyrogallol, catechol, alkylcatechol, Examples include hydroquinone, alkyl hydroquinone, phloroglucin, polyphenols such as bisphenol A, bisphenol F, bisphenol S, and dihydroxynaphthalene, and fats and oils such as cashew nut oil containing a phenolic compound. Halogenated phenols such as fluorophenol, chlorophenol, bromophenol and iodophenol can also be used, but it is preferable to use phenols which do not contain halogen from the environmental viewpoint. These can be used alone or in combination of two or more.

  The aldehyde used is not particularly limited, and examples thereof include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n-butyraldehyde, caproaldehyde, Examples include allyl aldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde, paraxylene dimethyl ether and the like. These may be used alone or in combination of two or more.

  Although it does not specifically limit as reaction molar ratio [F / P] at the time of making the said phenols (P) and aldehydes (F) react, It is preferable to set it as 0.5-0.9. Especially preferably, it is 0.55-0.87. By setting the reaction molar ratio within the above range, a phenol resin having a suitable molecular weight can be synthesized without gelation of the resin during the reaction. When the reaction molar ratio is less than the lower limit, the resin softening point of the obtained phenol resin may not be 70 to 130 ° C.

  The acidic catalyst used in this reaction is not particularly limited, but organic acids such as oxalic acid, mineral acids such as hydrochloric acid, sulfuric acid and phosphoric acid, diethyl sulfuric acid, paratoluenesulfonic acid, paraphenolsulfonic acid and the like can be used. it can.

  The phenol resin composition for a friction material according to the present invention can obtain an effect of flame retardancy by containing nitrogen. As a flame retardant mechanism by nitrogen, it is considered that nitrogen itself has lower combustibility than carbon, a nitrogen-containing inert gas is generated, oxygen is diluted, and fire extinguishing occurs due to a blocking effect. The nitrogen content of the phenol resin composition for a friction material is 4 to 30% by weight, preferably 5 to 25% by weight. When the nitrogen content is less than the lower limit, the effect of improving flame retardancy may not be sufficiently obtained. Further, when the nitrogen content is higher than the upper limit value, the substantial amount of the binder component is reduced, so that the mechanical strength may be lowered when the friction material is used.

  As a nitrogen source, a triazine compound obtained by reacting an aldehyde with at least one selected from the group consisting of melamine, melamine cyanurate, guanamine, adipoguanamine, benzoguanamine, acetoguanamine, succinoguanamine, melam, melem and melon ( b). Preferably, a methylol group, a methylol ether group, a melamine containing a dimethylene ether group, a melamine cyanurate, a guanamine, an adipoguanamine, a benzoguanamine, an acetoguanamine, a succinoguanamine, a melam, a melem, a melon derivative, a methylol group, The methylol ether group and the dimethylene ether group may be present alone or may contain these plural functional groups at the same time. In addition, melamine, melamine cyanurate, guanamine, adipoguanamine, benzoguanamine, acetoguanamine, succinoguanamine, melam, melem, and melon modified with phenols can be suitably used. These can be used alone or in combination of two or more. By using the triazine compound (b), the flame retardant component is effectively introduced into the resin skeleton at the time of forming the friction material, and the flame retardant improvement effect is enhanced. Even if the component is introduced, the mechanical strength can be hardly lowered.

  The aldehydes to be reacted with the triazine compound (b) are not particularly limited. For example, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n- Examples include butyraldehyde, caproaldehyde, allylaldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde, paraxylene dimethyl ether, and the like. Preferred are formaldehyde, paraformaldehyde, trioxane, and polyoxymethylene. These may be used alone or in combination of two or more.

  The method for mixing the triazine compound (b) with the novolak-type phenol resin (a) is not particularly limited. For example, pulverization mixing, pressure kneader, twin screw extruder, single screw extruder, kneading and mixing with a roll, resin Examples thereof include a method of once liquefying with heat or a solvent and then melt-mixing.

  Next, a method for obtaining a thermosetting phenol resin composition for friction material from the phenol resin composition for friction material of the present invention will be described. The thermosetting phenolic resin composition for a friction material of the present invention is obtained by adding a curing agent such as hexamethylenetetramine and, if necessary, a hardening accelerator to the phenolic resin composition for a friction material obtained by the above method. Can be obtained. The phenol resin material is, for example, a method in which a phenol resin and hexamethylenetetramine are melt-mixed, a method in which a phenol resin and hexamethylenetetramine are melt-mixed and then pulverized, and a phenol resin and hexamethylenetetramine pulverized respectively. It can be prepared by a dry mixing method or a method in which a phenol resin and hexamethylenetetramine are simultaneously pulverized and mixed.

  Although it does not specifically limit as a compounding quantity of a hexamethylenetetramine, It is preferable that it is 5-20 weight part with respect to 100 weight part of novolak-type phenol resins (a). More preferably, it is 6-17 weight part. If the amount of hexamethylenetetramine is less than the above lower limit, curing may be insufficient and dimensional accuracy may vary. When the above upper limit is exceeded, the gas generated by the decomposition of hexamethylenetetramine may swell in the friction material molded product and cause cracks and the like.

  In addition to the thermosetting phenol resin composition for a friction material of the present invention, an organic acid can be used as necessary for the purpose of accelerating the curing of the phenol resin. The amount of the organic acid used is not particularly limited, but 0.2 to 4 parts by weight can be added to 100 parts by weight of the novolak type phenol resin (a).

  The composition of this invention can be used suitably for manufacture of a friction material. When the composition of the present invention is used, for example, as a brake material, a brake can be produced by press-molding the composition of the present invention mixed with metal fiber, chemical fiber, cashew dust or the like.

  Hereinafter, the phenol resin composition for friction material of the present invention (hereinafter sometimes simply referred to as “resin composition”) and the thermosetting phenol resin composition for friction material (hereinafter simply referred to as “thermosetting resin composition”). However, the present invention is not limited to these examples. In the examples and comparative examples, “parts” and “%” are all “parts by weight” and “% by weight”.

(Resin synthesis example 1)
A mixture of 1000 parts of phenol, 570 parts of 37% formalin and 10 parts of oxalic acid was reacted at 100 ° C. for 3 hours, then dehydrated by atmospheric distillation until the temperature of the reaction mixture reached 140 ° C., and further up to 0.9 kPa, While gradually reducing the pressure, dehydration and demonomerization were performed by distillation under reduced pressure until the temperature of the reaction mixture reached 220 ° C. to obtain 905 parts of a novolak type phenol resin A905. The softening point of the novolac type phenol resin A was 88 ° C.

(Resin synthesis example 2)
After reacting a mixture of 1000 parts of phenol, 790 parts of 37% formalin and 10 parts of oxalic acid at 100 ° C. for 3 hours, 200 parts of butanol was added and dehydrated by atmospheric distillation until the temperature of the reaction mixture reached 140 ° C., Furthermore, dehydration and demonomerization were performed by distillation under reduced pressure until the temperature of the reaction mixture reached 230 ° C. while gradually reducing the pressure to 0.9 kPa, thereby obtaining 1012 parts of a novolac type phenol resin B. The softening point of the novolak type phenol resin B was 135 ° C.

(Resin synthesis example 3)
A mixture of 2000 parts of phenol, 900 parts of 37% formalin and 30 parts of oxalic acid was reacted at 100 ° C. for 3 hours, dehydrated by atmospheric distillation until the temperature of the reaction mixture reached 130 ° C., and further up to 0.9 kPa. While gradually reducing the pressure, dehydration and demonomerization were performed by distillation under reduced pressure until the temperature of the reaction mixture reached 200 ° C. to obtain 1003 parts of a novolak type phenol resin C100. The softening point of the novolak type phenol resin C was 67 ° C.

  Table 1 shows the blending amounts of the raw materials used in Examples and Comparative Examples. All numbers are parts by weight.

Example 1
Novolac type phenolic resin A and methylolated melamine resin (“PR-53235” manufactured by Sumitomo Bakelite) were blended in the proportions shown in Table 1, and pulverized and mixed with a small pulverizer to obtain resin composition A. 12 parts of hexamethylenetetramine was blended with 100 parts of the resin composition A, and pulverized and mixed with a small pulverizer to obtain a thermosetting resin composition A.

(Example 2)
Melting and mixing melamine-modified phenolic resin (“PR-55253” manufactured by Sumitomo Bakelite, 60% resin content) with a novolac-type phenolic resin A on a 150 ° C. hot plate so that the solid content weight is the ratio shown in Table 1. Resin composition B was obtained. Thereafter, hexamethylenetetramine was mixed in the same manner as in Example 1 to obtain a thermosetting resin composition B.

(Comparative Example 1)
A novolak-type phenol resin B and a methylolated melamine resin (“PR-53235” manufactured by Sumitomo Bakelite) were blended in the proportions shown in Table 1, and the resin composition C and the thermosetting resin composition were prepared in the same manner as in Example 1. C was obtained.

(Comparative Example 2)
A novolac type phenolic resin C and a methylolated melamine resin (“PR-53235” manufactured by Sumitomo Bakelite) were blended in the proportions shown in Table 1, and the resin composition D and the thermosetting resin composition were prepared in the same manner as in Example 1. D was obtained.

(Comparative Example 3)
A novolac type phenolic resin A and a methylolated melamine resin (“PR-53235” manufactured by Sumitomo Bakelite) were blended in the proportions shown in Table 1, and the resin composition E and the thermosetting resin composition were prepared in the same manner as in Example 1. E was obtained.

(Comparative Example 4)
A novolac type phenol resin A and a methylolated melamine resin (“PR-53235” manufactured by Sumitomo Bakelite) were blended in the proportions shown in Table 1, and the resin composition F and the thermosetting resin composition were prepared in the same manner as in Example 1. F was obtained.

(Comparative Example 5)
A novolac-type phenol resin A and melamine were blended in the proportions shown in Table 1, and a resin composition G and a thermosetting resin composition G were obtained in the same manner as in Example 1.

(Comparative Example 6)
Hexamethylenetetramine was blended with the novolac type phenol resin A in the ratio shown in Table 1 to obtain a thermosetting resin composition H.

(Evaluation)
The resin compositions obtained in the examples and comparative examples were evaluated in the following manner. A brake material was prepared and evaluated using a thermosetting resin composition obtained from the resin composition. 400 parts by weight of barium sulfate, 400 parts by weight of calcium carbonate, 50 parts by weight of cashew dust, 50 parts by weight of aramid fibers, and 100 parts by weight of the powdered thermosetting resin composition obtained in each of the examples and comparative examples To obtain a formulation. The obtained blend was molded at a temperature of 150 ° C. and a pressure of 400 kg / cm ² for 5 minutes to obtain a molded product of 100 mm × 100 mm. The obtained molded product was further fired at 200 ° C. for 5 hours to produce a brake material.

(Evaluation methods)
(1) Bending strength The obtained molded product was measured according to JIS K 7203 "Bending test method of hard plastic". The strength after heat treatment was measured for a sample subjected to normal strength at normal temperature and heat-treated at 350 ° C. for 4 hours.
(2) Flame retardance The obtained molded product was cut into a 10 mm cube with a diamond cutter, and the obtained test piece was put into a drying furnace heated in advance to 580 ° C., and the time from the start to the ignition was charged. It was measured.

Table 2 shows the evaluation results.

As shown in Table 2, the resin compositions of Examples 1 and 2 obtained by the present invention and the thermosetting resin compositions obtained from them were molded as compared with Comparative Example 6 in which no flame retardant was added. In spite of the fact that the normal strength of the body and the strength after heat treatment are almost the same, in the flame retardancy evaluation, it can be seen that the time to ignition becomes longer and the flame retardancy is improved.
On the other hand, in Comparative Example 1 using a phenol resin having a high softening point, a decrease in the strength of the molded product was observed due to insufficient fluidity of the resin. Further, in Comparative Example 2 using a phenol resin having a low softening point, the resin composition and the thermosetting resin composition were blocked, and a molded product could not be obtained.
Further, in Comparative Example 3 in which the nitrogen content is less than the above range, almost no improvement in flame retardancy is seen. Conversely, in Comparative Example 4 in which the nitrogen content is greater than the above range, flame retardancy is improved. The normal strength was greatly reduced. Further, when only melamine was used as the triazine compound, although the flame retardancy was improved, a decrease in the normal strength was observed.
From these results, by using the resin composition and the thermosetting resin composition obtained by the present invention, the flame retardancy is improved while maintaining the strength of the molded body, the phenol resin composition for friction material, and the friction It turned out that it is a thing excellent as a thermosetting phenol resin composition for materials.

Claims (4)

Selected from the group consisting of a novolak-type phenolic resin (a) having a resin softening point of 70 to 130 ° C., and melamine, melamine cyanurate, guanamine, adipogamine, benzoguanamine, acetoguanamine, succinoguanamine, melam, melem and melon A phenol resin for a friction material, comprising a triazine compound (b) obtained by reacting at least one selected from aldehydes and having a nitrogen content of 4 to 30% by weight of the total resin composition Composition. The phenol resin composition for a friction material according to claim 1, wherein the triazine compound (b) contains a methylol group, a methylol ether group, or a dimethylene ether group. The phenol resin composition for a friction material according to claim 1, wherein the triazine compound (b) includes a compound modified with phenols. The thermosetting phenol resin composition for friction materials which contains the hexamethylenetetramine as a hardening | curing agent in the phenol resin composition for friction materials of any one of Claims 1-3.