JP2001139767A - Novolak-type phenol resin composition and frictional material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phenol resin composition excellent in alkali resistance and flexibility, having fast-curability, good in moldability, and hardly having blocking properties because of a high melting point, and further to provide a frictional material by using the composition as a binder. SOLUTION: This triazine-modified novolak-type phenol resin composition is the one comprising a novolak-type phenol resin composed of phenols, triazines and aldehydes, and is characterized by the novolak-type phenol resin of a high- ortho type resin having >=1.0 rate of the ortho-position to the para-position (ortho-position/para-position) of the methylene bond to a phenol nuclear.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novolak-type phenolic resin composition and various molding materials using a friction material, a grinding wheel, and an organic / inorganic substrate using the composition as a binder. The novolak-type phenolic resin composition of the present invention is particularly suitable for applications requiring moldability, moisture resistance, alkali resistance, friction characteristics, and the like.

[0002]

2. Description of the Related Art Phenol resins have excellent heat resistance,
Utilizing adhesive properties, mechanical properties, electrical properties, price advantages, etc., molding materials for various substrates, binders for friction materials, binders for abrasives, adhesives for wood, binders for laminates, molds Widely used for binders and the like.

[0003] On the other hand, phenolic resins have the disadvantage that they are inferior in flexibility, alkali resistance, water resistance and adhesion.

[0004] Various modification techniques have been used to remedy this drawback. For example, polyvinyl butyral, nitrile rubber (NBR), SBR, polybutadiene, rubber having a carboxyl group or an amino group bonded to the terminal (CTB
(N, ATBN), an epoxy resin, a xylene resin, a silicon compound, a urethane compound, and the like can be modified by mixing or reacting with a phenol resin.

[0005] When these modifiers are used alone,
Alternatively, two or more modifiers may be used, and the amount of modification is appropriately selected and used so as to exert its purpose.
By using these known modifiers, it is possible to improve the brittleness of the phenolic resin and to some extent improve the physical properties such as flexibility and adhesiveness.

[0006] However, these modification techniques are often not sufficient for the demands of phenolic resins, such as improvements in alkali resistance, arc resistance, moisture resistance, flame retardancy, etc., and these methods are increasingly insufficient. As a technique for solving this problem in which the reforming technique has become an important issue, a novolak-type phenol resin modified with triazines has been proposed (Japanese Patent Application Laid-Open No. 8-31142). The novolak-type phenol resin is most commonly used together with hexamethylenetetramine (hereinafter referred to as "hexamine") as a curing agent, and is pulverized and thermally cured to be used as various binders. As performance requirements for phenolic resins, shortening of curing time for the purpose of shortening molding time has been required.

Hexamine is used as a curing agent, and a novolak-type phenolic resin or these modified phenolic resins and various base materials are mixed by a compression molding method or an injection molding method.
When molding, the use of a large amount of hexamine shortens the curing time.However, it becomes more difficult to remove the ammonia gas generated from hexamine during curing, and the molded product has a high hardness. If used,
There is a problem that the use of the modifier in an attempt to improve the brittleness is wasted.

As a production method for improving the curing rate, it is known to use a so-called high-ortho type novolak resin using a divalent metal salt such as a zinc acetate catalyst as a catalyst.

However, in order to prevent gelation during the production of this high-ortho novolak-type phenol resin, the charged molar ratio (F / P) of formaldehyde (F) to phenols (P) must be kept at a certain level or less. . For this reason, it is generally difficult to raise the melting point of the resin as compared with a random novolak type phenol resin. In addition, low-melting high-ortho novolak phenolic resin is in the solid state,
Alternatively, when powdered, there is a problem of fusion. This tendency is remarkable especially when various rubber modifications are performed for the purpose of imparting flexibility.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks of phenolic resins, that is, they are excellent in alkali resistance, flexibility and fast-curing type, and have good moldability. It is an object of the present invention to provide a phenol resin composition having a high melting point and no blocking property and a friction material using this composition as a binder.

[0011]

Means for Solving the Problems As a result of intensive studies in view of the above circumstances, the present inventors have found that when a modified phenolic resin is produced, phenols and triazines are co-condensed and a high ortho triazine modified phenolic resin is produced. Was found to be effective in solving the problem, and the present invention was completed.

That is, [I] the present invention relates to a novolak-type phenol resin composition comprising a novolak-type phenol resin comprising a phenol, a triazine and an aldehyde, wherein the novolak-type phenol resin is used for a phenol nucleus. It is intended to provide a triazine-modified novolak-type phenol resin composition characterized by being a high ortho-type resin having a ratio (ortho / para) of an ortho bond to a para bond of a methylene bond of 1.0 or more. II] The present invention provides the triazine-modified novolak-type phenolic resin composition according to the above [I], wherein the triazine is at least one member selected from the group consisting of melamine, acetoguanamine and benzoguanamine. [III] The present invention does not include hexamethylenetetramine as a curing agent. It is intended to provide the triazine-modified novolak-type phenol resin composition according to the above [I] or [II], and [IV] the present invention provides a method wherein the novolak-type phenol resin comprises a catalyst comprising a phenol, a triazine and an aldehyde. The present invention provides a triazine-modified novolak-type phenolic resin composition according to any one of the above [I] to [III], which is obtained by polymerizing using a divalent metal salt. A friction material comprising the triazine-modified novolak-type phenol resin composition according to any one of [1] to [IV].

The novolak type phenolic resin of the present invention comprises:
Particularly, a divalent metal salt is used as a reaction catalyst to react phenols, triazines, and aldehydes, and contains almost no unreacted triazines and a structure in which a high ortho-type phenol resin and a triazine / phenol cocondensate are mixed. Have. Due to this structural feature, the phenol resin has the disadvantages of alkali resistance, arc resistance, flame retardancy, rapid curing property, and high melting point and blocking resistance, which are disadvantages of phenol resin.

The novolak-type phenol resin having a triazine ring has good friction characteristics in addition to the above characteristics when used as a friction material, ie, a binder for a brake lining, a disc pad, a clutch facing, a brake shoe and the like. It has the characteristic that.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described more specifically.

The phenols for obtaining the phenolic resin of the present invention are not particularly limited. For example, phenol, alkylphenols such as cresol, xylenol, ethylphenol, butylphenol, nonylphenol, octylphenol, and bisphenol A , Bisphenol F, bisphenol S, resorcinol, polyhydric phenols such as catechol, halogenated phenol, phenylphenol,
Aminophenol and the like. The use of these phenols is not limited to one kind alone, and two or more kinds can be used in combination. Further, the compound containing a triazine ring used in the phenolic resin composition of the present invention is not particularly limited,
For example, a compound represented by the following general formula (I) can be mentioned.

[0017]

Embedded image

(Wherein R1, R2, and R3 are amino groups, alkyl groups, phenyl groups, hydroxyl groups, hydroxylalkyl groups, ether groups, ester groups, acid groups, unsaturated groups,
Specific examples of the compound represented by formula (I) include melamine, guanamine derivatives such as acetoguanamine and benzoguanamine, cyanuric acid, methyl cyanurate, and ethyl cyanurate. , Acetylcinnurate, cyanuric acid derivatives such as cyanuric chloride, and the like. Among these, guanamine derivatives such as melamine, acetoguanamine and benzoguanamine in which any two or three of R1, R2 and R3 are amino groups are preferred. In using these compounds containing a triazine ring, it is not limited to only one kind,
It is also possible to use two or more kinds in combination.

The aldehyde for obtaining the phenolic resin composition of the present invention is not particularly limited, but formaldehyde is preferred from the viewpoint of easy handling. Formaldehyde includes, but is not limited to, formalin, paraformaldehyde, and the like as typical sources.

The catalyst for increasing the ortho / para position (referred to as o / p ratio) of the methylene bond to the phenol nucleus of the present invention is not particularly limited, but divalent metal salts and metal oxides are preferably used. . Examples of the catalyst include, for example, zinc acetate, lead acetate, zinc oxide, zinc borate, zinc octylate, manganese borate, and the like, and a single or a mixture of these can be used.

The o / p ratio of the methylene bond to the phenol nucleus of the present invention is represented by the following formula. That is, o / p ratio = {(number of methylene bonds bonded at ortho positions) + (1/2 of methylene bonds bonded at ortho positions and para positions)} / {(bonds at para positions Number of methylene bonds) + (1/2 of the number of methylene bonds bonded at the ortho and para positions)｝ The o / p ratio can be easily determined by nuclear magnetic resonance (13C-NMR). it can. This o / p ratio is substantially 1.0 or more, and this upper limit is not particularly limited, but is not limited to 4.
It is preferably 0 or less. Further, the o / p ratio is 1.2 to
3.5 is a more preferred range. If it is less than 1.0, the curing speed is not increased and the moldability is not improved. On the other hand, if it exceeds 4.0, the curing rate may be too high depending on the amount of the curing agent, and problems such as difficulty in degassing timing during molding may occur. However, even when the value exceeds 4.0, practical use is not impossible by adjusting the amount of hexamine. Next, a method for producing the triazine-modified novolak type phenol resin of the present invention will be described. Although not particularly limited, for example, the following method may be used.

That is, (1) a step of adjusting the pH of the system using the above-mentioned mixture of phenols, triazines and aldehydes using a catalyst, and (2) reacting the mixture under conditions where the aldehydes do not volatilize. (3) removing the reaction water in the system, (4) converting the dimethylene ether bond in the molecule generated by the reaction into a methylene bond, and (5) removing the unreacted phenol monomer. Can be obtained by sequentially passing through the respective steps. Hereinafter, each step will be described. The ratio of the phenols to the triazines in the first step is not particularly limited. For aldehydes, the reaction to triazines takes precedence over the reaction to phenols, and the amount of aldehydes that react with phenols decreases.As a result, it becomes impossible to exhibit a high ortho-type effect. ,
What is necessary is just to use the minimum amount which contributes to the improvement of the alkali resistance, arc resistance, flame resistance and the like of the phenol resin. That is, phenols: triazines in a molar ratio of 1: 0.01 to 2.
It is preferably 0.

The ratio of aldehydes to (phenols + triazines) is not particularly limited. However, if the aldehydes are too large, a large amount of methylol groups will remain in the phenol resin, which is not preferable. 0.
It is preferably 2 to 0.9: 1. When a divalent metal salt or the like is used as a catalyst, the pH is usually 4.0 to 6.0.
It becomes 0. The condition in the second step in which the aldehyde is not volatilized refers to a recirculation condition for returning volatile components in the system to the system, and refers to a case where the reaction is carried out near the boiling point of a low-boiling substance in the system. By reacting all of the aldehydes, a resin designed at a charged molar ratio can be stably obtained with good reproducibility. At the time of this reaction, the reaction can be performed in the presence of various solvents from the viewpoint of reaction control. Although it does not specifically limit as a solvent, For example, toluene, xylene, methyl isobutyl ketone, ethylene glycol monomethyl ether, N, N-
Dimethylformamide and the like. These solvents can be used alone or as a mixed solvent of two or more kinds as appropriate. Thereafter, if necessary, washing with water is performed to remove catalyst residues and impurities. The method of removing the reaction water in the third step is not particularly limited, but it is preferable to heat the system to a temperature of 120 ° C. or higher. The method of converting the dimethylene ether bond in the molecule generated by the reaction into a methylene bond in the fourth step is not particularly limited,
A method of repeating the second step and the third step is exemplified. There is no particular limitation on the removal of the unreacted phenol monomer in the fifth step. For example, when the temperature of the system is set to 150 ° C. or higher, preferably 170 ° C. or higher and distillation is performed under vacuum, the unreacted monomer is removed together with the reaction water. Are excluded. As a method for curing the triazine-modified novolak type phenol resin of the present invention, a method using hexamine as a curing agent is generally used. The quantity is generally 3
It is about 20 parts by weight, but considering the adjustment of the curing rate and the hardness of the cured product, 3 to 15 parts by weight is an appropriate amount. As a form of adding hexamine, a method of mixing the obtained solid resin with hexamine and pulverizing, or a method of mixing the solid resin and hexamine using a heat mixer such as a kneader or a roll may be used. Further, the obtained solid resin can be used by dissolving it in a solvent such as methyl ethyl ketone or ether together with hexamine. The novolak type phenolic resin of the present invention not only uses hexamine as a curing agent, but also a substance that reacts with a phenolic OH group and an NH group of triazines, for example, a substance having a polyglycidyl group having two or more functional groups,
It is also possible to use a compound having a carboxyl group, a substance having an ethylenically unsaturated double bond, or the like, and it can be used together with hexamine. Also in this case, a cured product having excellent physical properties can be obtained in that the modified phenol resin of the present invention does not contain unreacted triazines. The triazine-modified novolak-type phenol resin of the present invention can be further blended or reacted with another modifier. Applications of the triazine-modified novolak type phenolic resin composition of the present invention include, for example, resin curability, alkali resistance, arc resistance, and friction properties of the cured product, and compatibility with various organic and inorganic molding materials and rubber. It can be suitably used as a rubber compounding agent and a binder for a grinding material such as a grindstone, etc., and can be used particularly as a friction material by utilizing the friction characteristics of a triazine ring.

That is, it is useful as a binder for brake lines, disc pads, clutch facings, and brake shoes. A friction material using the phenolic resin composition of the present invention as a binder for a friction material can be produced according to a conventional method. That is, it can be obtained by adding a fiber base material and a curing agent to the phenol resin composition and thermally curing the composition.

Examples of the fiber base include inorganic fibers such as glass fibers, ceramic fibers, carbon fibers, copper fibers, brass fibers, and stainless steel fibers, metal fibers, natural fibers such as cotton and hemp, polyesters, and polyamides. Synthetic organic fibers and the like. These fibers may be used alone or in combination of two or more. The shape of the fibrous base material is not limited at all, and any shape such as short fibers, long fibers, yarns, mats, and sheets may be used. As the curing agent, those described above can be used. The conditions for thermally curing the composition are not particularly limited, and the composition can be cured under ordinary conditions for curing a phenol resin.
That is, the temperature at which the resin component is usually softened is 130 ° C. or higher2
Perform at a temperature of 00 ° C. or less. At this time, it is preferable to perform the heating at a temperature in the range of 130 to 180 ° C. in order to prevent molding defects. In order to obtain a friction material having more excellent heat resistance, it is preferable to perform post-firing after molding. When the triazine-modified novolak-type phenolic resin composition of the present invention is used as a friction material, a filler, an additive, and the like can be further added.

Known fillers and additives can be used, for example, silica, barium sulfate, calcium carbonate, silicon carbide, cashew oil polymer, molybdenum disulfide,
Examples include aluminum hydroxide, talc, clay, graphite, graphite, rubber particles, aluminum powder, copper powder, and brass powder. These fillers and the like may be used alone or as a mixture of two or more.

When mixing the above-mentioned friction material raw materials, for example, if a cashew oil polymer or a fibrous raw material having a large particle diameter is coated in advance with a liquid resin such as a water-soluble phenol resin, uneven distribution of each component at the time of mixing the raw materials is achieved. It is preferable to prevent Also, the amount of these raw materials used can be adjusted according to the application and required performance.

[0028]

The present invention will be described more specifically below with reference to examples. However, the present invention is not limited only to the following embodiments.

Example 1 940 parts of phenol and 100 parts of benzoguanamine added 4 parts
429 parts of 1.5% formalin and 3 parts of zinc acetate were added, and the temperature was gradually raised to 100 ° C. while paying attention to heat generation.
After reacting at 100 ° C. for 3 hours, the temperature was raised to 130 ° C. over 2 hours while removing water under normal pressure. Next, after reacting for 1 hour under reflux, the temperature was raised to 160 ° C. while removing water under normal pressure. Next, unreacted phenol was removed under reduced pressure to obtain a phenol resin composition having a softening point of 125 ° C.

The o / p ratio of the phenolic resin composition determined by 13 C-NMR was 2.0. The amount of unreacted benzoguanamine was 0%.

Example 2 To 940 parts of phenol and 140 parts of benzoguanamine,
429 parts of 1.5% formalin and 3 parts of zinc borate were added, and the temperature was gradually raised to 100 ° C. while paying attention to heat generation. After reacting at 100 ° C. for 3 hours, the temperature was raised to 130 ° C. over 2 hours while removing water under normal pressure. Next, after reacting for 1 hour under reflux, the temperature was raised to 160 ° C. while removing water under normal pressure. Next, unreacted phenol was removed under reduced pressure to obtain a phenol resin composition having a softening point of 120 ° C.

The o / p ratio of the phenolic resin composition determined by 13 C-NMR was 1.7. The amount of unreacted benzoguanamine was 0%.

Example 3 To 940 parts of phenol and 140 parts of melamine, 41.5%
A formalin part and 3 parts of zinc acetate were added, and the temperature was gradually raised to 100 ° C. while paying attention to heat generation. 3 at 100 ° C
After reacting for hours, water was removed under normal pressure while 130
The temperature was raised to 2 ° C over 2 hours. Next, after reacting for 1 hour under reflux, the temperature was raised to 160 ° C. while removing water under normal pressure. Next, unreacted phenol was removed under reduced pressure to obtain a phenol resin composition having a softening point of 130 ° C.

The o / p ratio of the phenol resin composition determined by 13 C-NMR was 1.9. The amount of unreacted melamine was 0%.

Example 4 8 parts were added to 940 parts of phenol and 140 parts of benzoguanamine.
228 parts of 0% paraform and 3 parts of zinc acetate were added, and the temperature was gradually raised to 100 ° C. while paying attention to heat generation. 100
After the reaction at 3 ° C. for 3 hours, the temperature was raised to 130 ° C. over 2 hours while removing water under normal pressure. After reacting at 130 ° C. under reflux for 1 hour, the temperature was raised to 160 ° C. while removing water under normal pressure. Next, unreacted phenol was removed under reduced pressure to obtain a phenol resin composition having a softening point of 125 ° C.

The o / p ratio of the phenolic resin composition determined by 13 C-NMR was 2.4. The amount of unreacted benzoguanamine was 0%.

Example 5 92% to 940 parts of phenol and 94 parts of benzoguanamine
223 parts of paraform, 200 parts of xylene and 6 parts of zinc acetate were added, the temperature was raised to 110 ° C. while paying attention to heat generation, and the temperature was gradually raised to 130 ° C. for 3 hours using a decanter apparatus. After further reacting at 130 ° C. under reflux for 1 hour, the temperature was raised to 160 ° C. while removing water at normal pressure. Next, unreacted phenol was removed by reducing the pressure, and the softening point was 128 ° C.
Was obtained. The o / p ratio of the phenol resin composition determined using 13 C-NMR was 2.9.
The amount of unreacted benzoguanamine was 0%. Comparative Example 1 41. phenol 940 parts, benzoguanamine 94 parts.
429 parts of 5% formalin and 4 parts of triethylamine were added to adjust the pH of the system to 8.2, and the temperature was gradually raised to 100 ° C. while paying attention to heat generation. After reacting at 100 ° C. for 5 hours, the temperature was raised to 120 ° C. over 2 hours while removing water under normal pressure. Next, after reacting for 3 hours under reflux, the temperature was raised to 140 ° C. over 2 hours while removing water under normal pressure. After reacting for 3 hours under reflux, the temperature was raised to 160 ° C. over 2 hours while removing water under normal pressure. After further reacting under reflux for 3 hours, the temperature was raised to 180 ° C. over 2 hours while removing water under normal pressure. Next, unreacted phenol is removed under reduced pressure, and the
A phenolic resin composition at 0 ° C. was obtained.

The o / p ratio of the phenolic resin composition determined by 13 C-NMR was 0.92. Comparative Example 2 Phenol (940 parts), melamine (120 parts), 41.5% formalin (450 parts) and 48% sodium hydroxide (6 parts) were added, the pH of the system was adjusted to 8.2, and the mixture was reacted at 100 ° C. for 2 hours. Next, the temperature was raised to 180 ° C. while removing water under normal pressure, and unreacted phenol was removed under reduced pressure to obtain a phenol resin composition having a softening point of 118 ° C. 13C-
The o / p ratio of the resin composition determined using NMR was 0.8.

Comparative Example 3 940 parts of phenol, 434 parts of 41.5% formalin,
Add 3 parts of zinc acetate, raise the temperature to 100 ° C while paying attention to heat generation,
The reaction was performed at 100 ° C. for 4 hours. Next, the temperature was raised to 130 ° C. while removing water under normal pressure. After reacting at 130 ° C. for 1 hour under reflux, the temperature was raised to 160 ° C. while removing water under normal pressure, and then unreacted phenol was removed under reduced pressure to obtain a phenol resin composition having a softening point of 86 ° C. Was.

The o / p ratio of the phenolic resin composition determined by 13 C-NMR was 2.5. 10 parts of hexamine was added to 90 parts of the phenolic resin obtained in the above Examples and Comparative Examples, and the mixture was pulverized and mixed with a fine pulverizer, and the following test method was performed. <Test Method and Evaluation Criteria> Curing speed; time required for adding hexamine to the phenolic resin obtained in Examples and Comparative Examples, pulverizing and mixing with a fine pulverizer, and curing on a cure plate at a hot plate temperature of 150 ° C. Was measured and defined as a gel time.

Solidification property: 100 g of resin was put in a polyethylene bag, and after heat sealing, it was left for 30 days in a place at 30 ° C. × 70% relative humidity to observe the solidification state.

After thoroughly mixing 70 parts of glass powder (70M-10A manufactured by Nippon Electric Glass) with 30 parts of each finely pulverized product, the mold surface temperature was 150 ° C. and the pressure was 150 kg.
/ Cm ² , including 4 times of degassing, for a total of 10 minutes. After taking out from the mold and after-curing at 180 ° C. for 3 hours, a sample was cut out for a bending strength test piece. Bending strength measurement is normal strength and 0.5% Na
The alkali resistance when boiling in an OH solution for 5 hours was measured. Table 1 shows the test results.

[0043]

[Table 1]

The modified novolak type high ortho phenol resin of the present invention is clearly superior to the non-hyortho phenol resin. The solidification of the powdered resin was good for all of the modified phenolic resins, while the solidification of the unmodified one was solidified. As for the alkali resistance, it can be seen that the phenolic resin of the present invention is much superior to the comparative examples. In particular, the retention rate is about twice that of the unmodified phenol resin. Application example (production of friction material)

[0045]

[Table 2]

The blends shown in Table 2 were uniformly mixed while the fibers were opened, and the phenolic resins (mixed and ground with 10% hexamine) prepared in the Examples and Comparative Examples were respectively changed to prepare ones. At a normal temperature of 300 kg / cm ² at a mold temperature of 150 ° C. and a pressure of 150 kg / cm ² ,
The molded product was cured by heating for 10 minutes, and the molded product was cured after 160 ° C. for 5 hours and 200 ° C. for 3 hours, and cut out for a friction test. Coefficient of friction; measured according to JISD-4411.

[0047]

[Table 3]

Table 3 shows that the friction materials using the phenolic resin compositions of Examples 1 to 5 exhibited a high and stable friction coefficient from low to high temperatures with respect to the friction materials of Comparative Examples 1 to 3.

[0049]

The high ortho- / para-orientation-oriented high-ortho-type triazine-modified resin of the present invention is excellent in quick-curing properties, moldability, alkali resistance and frictional properties, and its pulverized products and solid products are resistant to blocking. Because of its excellent properties, it is useful as a binder for various molding materials and friction materials.

Claims (5)

[Claims] 1. A novolak-type phenolic resin composition comprising a novolak-type phenolic resin comprising a phenol, a triazine and an aldehyde, wherein the novolak-type phenolic resin has an ortho position of a methylene bond to a phenol nucleus. Para position ratio (ortho position / para position)
Is a high ortho-type resin having a molecular weight of 1.0 or more. 2. The triazine-modified novolak-type phenolic resin composition according to claim 1, wherein the triazine is at least one member selected from the group consisting of melamine, acetoguanamine and benzoguanamine. 3. The triazine-modified novolak type phenol resin composition according to claim 1, which comprises hexamethylenetetramine as a curing agent. 4. A novolak-type phenol resin comprising a phenol, a triazine and an aldehyde as catalysts.
The triazine-modified novolak-type phenol resin composition according to any one of claims 1 to 3, which is polymerized using a valent metal salt. 5. A friction material comprising the triazine-modified novolak-type phenolic resin composition according to claim 1.