JPS60108459A - Thermostable phenol resin forming material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to thermostable phenolic compositions.

Relating to phenolic compositions.

[Prior art] and [Problems to be solved by the invention] Phenolic resins, especially glass m,! 11. It is well known to those skilled in the art that phenol-formaldehyde polymers reinforced with inorganic fillers have excellent dimensional stability even under high loads and high temperatures.

In fact, phenol-formaldehyde compounds
It is generally known that it has better resistance to thermal degradation at high temperatures than most other common polymeric materials. However, it would be possible to obtain a phenol composition that is more resistant to deterioration and does not lose much of its properties as the aging time increases, even at higher temperatures than that found in the conventionally known technology of phenolic molded dung powder. It is believed that its uses and effectiveness will further increase.

[Means for Solving the Invention] and [Operation] The present invention provides a phenolic resin molding composition with improved resistance to deterioration at high temperatures, (1) an elastomer that becomes brittle with aging, such as a butadiene-based molding composition; rubber and/or (2) molecular sulfur or a sulfur-donating component.

A preferred phenolic composition of the present invention comprises a phenolic novolac resin and/or resol resin, glass fiber and/or fibrous reinforcement, a particulate inorganic filler, and other commonly used additives such as a hardening accelerator, In addition to the mixture of crosslinking agent, mold release agent and pigment, sulfur compounds and/or butadiene rubber-type elastomeric heat-stable additives are added. The molding materials of the invention can be processed by any conventional method, such as compression, transfer or injection molding.

In the present invention, heat aging of a glass fiber reinforced phenonyl compound is surprisingly surprising, with both the sulfur additive and the elastomer initially crosslinking, i.e. becoming brittle rather than softening with aging. It can be improved. Applicants have found that when these two additives are used alone they improve the heat aging of phenolic molded dough, but what is even more surprising is that when both the butadiene rubber and the sulfur compound are used together It was discovered that a synergistic effect can be obtained when used. If you experiment,
The combined thermal stabilization effect was found to be more than twice the expected linear cumulative result. Therefore, whether alone or in synergistic combination, these additives have the properties of exceptionally good retention of weight, molded dimensions and mechanical properties even after prolonged exposure to high temperatures, all of which they bring to the present invention. It is.

These and other advantages of the present invention will be apparent and understood by those skilled in the art from the following detailed description, examples, and accompanying drawings.

According to the present invention, a phenolic resin molding composition with improved heat resistance comprises: (1) an elastomer that becomes brittle with aging;
For example, it can be made by adding either a butadiene rubber and/or (2) molecular sulfur or a sulfur donating component. The improved phenolic composition preferably consists of a mixture of the following components: (1) one or more thermoset phenolic novolak resins and/or resol resins (2) glass fibers and/or other fibers. (3) a combination of one or more particulate inorganic fillers; (4) other additives commonly used in phenolic molding compositions, such as hardening accelerators, crosslinkers, mold release agents, pigments; (5) aging. Elastomers that become brittle, such as butadiene rubber and/or molecular sulfur or a sulfur-donating component. Phenol-formed Hungbounds, consisting of components (1) to (4) above, are commercially available and known to those skilled in the art.

Phenolic resins useful for the present invention are also known to those skilled in the art. These resins consist of several different phenols combined with aldehydes. The phenol monomers used include substituted phenols,
For example, resorcinol, para-t-butylphenol,
These include para-phenylphenol, cresol, xylenol and other alkylated phenols. Many aldehydes can also be used. For example, formaldehyde, paraformaldehyde 1. These are acetaldehyde, butyraldehyde, and furfuraldehyde. These resins are cured by heating and/or with a curing agent to create a crosslinked structure. Novolaks and resols are two basic types of phenolic resins that can differ depending on the catalyst to phenol-formaldehyde ratio used during preparation, and the reactivity. Those having a molar ratio of soenol to aldehyde of 1 or less are usually called novolaks.

Hardening agents, such as hexamethylenetetramine (hereinafter referred to as Hex)
a) is necessary to crosslink the novolak.

Resoles occur when the phenol to aldehyde ratio is above 1 and contain reactive groups that require only heating for crosslinking.

Phenol-formaldehyde based phenolic resins are preferred and are commercially available. Other preferred resin components are one or a combination of novolac resins and/or resol resins. for example,
It is often desirable to mix novolacs of different molecular weights to fully control molding rheology or cure rate. The amount of resin used ranges from about 15 to about 40 percent by weight of the total composition depending on the desired final properties. In compositions containing novolac resins, it is preferred to minimize the H1IX& content to allow sufficient crosslinking in the final molded product. Excessive Hexa content gives a form w to heat resistance. Minimizing the Hθxa content often facilitates its partial replacement with other formaldehyde donating compounds such as anhydrous formaldehyde aniline, resols, melamine/formaldehyde, epoxy resins.

The composition of the present invention usually contains 10 to 40% by weight of total fibrous reinforcing agent. A preferred reinforcing agent is glass fiber, either in crushed or cut fibrous form.

Other fibers include aramid, asbestos, carbon,
Cellulose, ceramic, combinations thereof, and any combination thereof with other fibers used in industrial phenolic molding compositions.

The presence of ionic contaminants and/or surface reactivity is an important consideration in selecting a suitable filler. It has been found that weakly acidic fillers improve heat resistance. Useful fillers include particulate minerals such as silica, calcium silicates (wollastonite), hydrated clays, powdered glasses, glass beads and mixtures thereof. Hydrated clays are preferred fillers because they provide good heat aging results, especially in clay-containing compositions. The filler or combination of fillers can be used in amounts ranging from about 5 to about 50% by weight of the total composition.

The addition of certain crosslinking agents is believed to be beneficial to the heat resistance of glass reinforced phenolic compounds in this invention. Examples of strong crosslinking agents include r-aminopropyltriethoxysilane, n-β-(aminoethyl)-r-aminopropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, α- Glycidoxypropyltrimethoxysilane, α-mercaptopropyltrimethoxysilane and ureido-modified amino crosslinking agent. Usually, the powder of the present invention also contains a curing accelerator. For example, total addition of metal oxides such as lime, magnesium oxide, zinc oxide and mixtures thereof
- This is often done to accelerate the curing reaction. usually,
The composition contains from about 0.5% to about 5.0% by weight of this accelerator. The selection of the specific accelerator is extremely important. Both lime and zinc oxide were found to be more detrimental to heat resistance than magnesium oxide.

The composition of the present invention also contains various mold release agents and pigments. A mold release agent is any additive commonly used for this purpose in phenolic compounds. Examples are calcium stearate, zinc stearate, stearic acid and various combinations thereof. This mold release agent can be used in high amounts, but is usually used in amounts ranging from 0.5 to 3.0% by weight.

As the elastomer that becomes brittle with age, such as butadiene rubber, any one of a number of commercially available polymers can be used in the present invention. Latex and powder forms are most convenient for optimal dispersion into molded dung-pounds. Common rumors of substances effective for heat resistance according to the present invention include acrylonitrile-butadiene copolymer latex, powdered acrylonitrile-butadiene copolymer (pre-crosslinked), butadiene-styrene-vinylpyridine terpolymer latex, butadiene-styrene copolymer latex, carboxy It is a terminal butadiene-styrene copolymer latex.

In the present invention, particularly good results are obtained from compositions containing from about 3.0 to about 8.0% by weight of said rubber. The addition of rubber deteriorates the mechanical and electrical properties of the phenolic composition,
It is known that water absorption rate, surface hardness, and moldability are deteriorated. Due to the fact that increasing rubber content deteriorates properties, rubber should be added only in effective amounts, i.e., in amounts that improve heat aging properties without adversely affecting mechanical, electrical properties, moldability, and water absorption. It turns out that it is enough to add it.

Similarly, currently the effective amount of sulfur-based additives is approximately 0.1
9 to about 1.6% by weight. As mentioned above, molecular sulfur and sulfur donating compounds have been found to improve overall heat aging properties of phenolic molding compositions. Preferred sulfur-donating compounds include tetramethylthiuram disulfide (TMTD).
, 2,2'-dithiobisbenzothiazole (MBTS
) and optionally morpholine disulfide (sulfasan S
), -tetramethylthiuram sulfide (Unazu), and dipentamethylenethiuram hexasulfide (Tetrone A).

〔Effect of the invention〕

The molding compounds obtained according to the invention can be processed in conventional manner, such as compression, transfer, injection molding, under conditions similar to those of other phenol powders. Excellent features of the finished molded product←
←→ indicates excellent retention of weight, dimensions, and mechanical properties during aging at high temperatures. These compositions containing relatively large amounts of rubber were also found to have good drop weight impact resistance (tenacity) and modulus.

Phenolic resin (2) + to improve tenacity
) It is known to those skilled in the art to add rubber,
The power achieved by the present invention using butadiene-based dung powder,
The heat resistance is unexpectedly superior to other commercially available rubber-filled phenolic materials.

〔Example〕

Hereinafter, the present invention will be described in further detail with reference to examples and drawings, but these are not intended to limit the invention in its entirety. In the following description, parts and percentages are by weight unless otherwise specified.

Example 1 In this example, four formulations were prepared. (A) is a control, and three (B), (0), and (D) are suitable for the present invention. Control formulation (A) contains neither rubber nor sulfur additives. Formulation (B) contains acrylonitrile-butadiene latex and molecular sulfur.

The comb latex contains approximately 40% by weight of uncrosslinked, 45% bound acrylonitrile content rubber.

Composition (0) contains all rubber latex but no sulfur. The fourth formulation (]) is a crosslinked acrylonitrile-butadiene copolymer with about 40% bound acrylonitrile. Details of each formulation are as follows: Composition A (Control) B OD Glass fiber α4 inch) 35.65 35.58 3
5.64 35.61 Silane 1.27 1.27 1
．． 27 1.27 ethanol (0,85) (0,8
5) (0,85) (0,85) Acrylonitrile-
Butadiene Latex 0 6.35 6.37 0
Granular acrylonitrinodobutadiene copolymer 0
0 0 6.35 Stearic acid 0.42 0.42
0.42 0.42 Calcium stearate 0.49
0.49 0.49 0.49 Magnesium oxide 1
．． 16 1.17 1.16 1.16 sulfur F700.1
900.19 Clay 29.1829.12 29.17 29.14
Hexa acid ile spear phenol novolac 31.5
5 25.14 26.02 25.10 Lime 0.2
7 0.27 0.27 0.27 water (10,61)
(10,59) (10,61) (10,60) Total amount (dry) 99.99100.0 100.0 1
00.0 glass fibers were first pretreated with a mixture of silane and ethanol 1. Ta. This is done by pouring the liquid in portions onto the glass in a polyethylene bag and then stirring the bag until the glass is evenly wetted. The ingredients of the formulation were first dry mixed in a Baker Birkins Sigma mixer and then in a latex chamber.
The pre-treated glass added to the mixer? mixed together with other ingredients. Total mixing time in the Sigma mixer was approximately 20 minutes.

This mixture was then compounded in a single screw extruder equipped with a die plate having a 5/8 inch diameter orifice. Water was fed as a processing aid to the extruder along with the mixed composition.

The extrudate was cooled to room temperature and then milled through a 578-inch mill to produce a granular molding material. Alfur and moisture were removed by drying. A final volatile content of about 4.0% was found to be nearly optimal, as judged by the weight loss of the soybeans exposed to 160° C. for 20 minutes.

Test sample bars (5 x 1/2 x 1/B inches) were then made by transfer molding this particulate material.
A post-baking treatment was performed at 88° C. for 4 hours.

This post-molding baking operation serves to at least partially restore the loss of bending strength and hardness caused by the rubber addition.

The heat aging test was conducted as follows.

A bar with nominal dimensions of 1/2 x 1/B x 5 inches was made by transfer molding. These materials were breformed, radio frequency preheated to about 240° C. below (116° C.), and molded in end gate female molds. The transfer pressure was varied depending on the plasticity of the molding material.

The nominal molding temperature was 335 below (168°C) and the curing time was 2 minutes.

This bar sample was post-baked before the oven aging test. 6 hours at 350”F (177°C), 375”F
A staged baking cycle of 4 hours at (191° C.) was applied throughout this work. Following the post-baking treatment, the bars were cooled to room temperature, weighed and then weighed for 2 hours.
It was placed in a furnace stabilized at 70°C.

Samples with some post-baking treatment @, ASTM D
790-81, method engineering, operating corporation, the test was carried out at room temperature to determine the bending strength, and the initial (unaged) strength was obtained. Samples were periodically sampled from the aging oven to measure weight and bending strength changes. Then 10% weight loss and 50
The % bending strength loss both times were estimated by graphical interpolation of the data. The results are shown in the table below.

Volatile content (%) 4.0 4.1 4.3 3.9 Bending strength (psi, baking treatment) 21,20020.6
00 19,900 20.000 Flexural modulus (10'
psi, baking treatment > 3.01 2.18 2.
18 2.35 Time for 10% weight loss (270°C, hours) 155 785 390 795 Time for 50% bending strength loss (270°C, hours) 130 770 330
810 The results show that the present invention dramatically improves both weight and bending strength retention. The rubber and sulfur containing materials (B, D) show approximately 6 times improved flexural strength retention at 270° C. over the unmodified control (A). Furthermore, it is believed that the pre-crosslinked powdered rubber (D) and the uncured latex (B) work equally well. Finally, a completely rubber-containing, sulfur-free composition (0
) is not very large, but it shows that this change is effective. Note that the bending strength and bending modulus data in all tables are initial values obtained from test rods before aging at 270°C.

Example 2 Hun Pound 'E=z''XGk was made using sulfur alone, Comb alone, powdered rubber and twice the amount of sulfur described above.

These dung pounds have the same general composition as B, except that the sulfur and rubber have been changed as indicated, and the phenol content has been adjusted in each case to a total of 1, depending on the amount of sulfur and rubber.
It has been adjusted to be 00 copies. These materials are
It was prepared and tested in the same manner as in Example 1. The results are shown in the table below.

Group g] 10'F G Powdered acrylo double lit butadiene copolymer 0
6.37 6.34 Sulfur 0.19 0 0.38 Other glass fiber (1/8 inch) 35.58 35.65
35.51 Silane 1.27 1.27 1.27 Ethanol (0,85) (0,85) (0,85)
Stearic acid 0.42 0.42 0.42 Calcium stearate 0.49 0.49 0.49 Magnesium oxide 1.17 1.17 1.17 Clay 29
．． 12 29.18 29.06 Phenol novolak containing Hexa hardener 31.49 25.19 25
．． 09 lime 0.27 0.27 0.27 A(-1-(10,59) (1(door fil) (10
,57) Total amount (dry) 100.0 100.0 1
00.0-J- Volatile content (%) 4. ．． 4 4.4 4.0 Bending strength (p
si, baking” treatment) 22.000 17,30
0 18.600 Flexural modulus (10'psi, baking > 3.03 2.28 2.34 10% weight loss time (270°C, hours) 235 410 8755
0% bending strength loss time (270°C, hours) 235 3
90 840 From these results, heat aging is significantly improved when either rubber or sulfur is added alone, and when both rubber and sulfur are added? It can be seen that the improvement is even better when used.

This is an important advantage since improved aging life is possible with the addition of small amounts of sulfur alone without essentially changing the other properties of the compound. 0 with 6.3% rubber
．． Using 38% sulfur (compound G)
As opposed to 0.19% sulfur (Hun Pound B or D
), aging lifespan from 785 or 795 hours to 875
There will simply be a slight increase in time.

When the results of the dung pound of this example and the dung pound of Example 1 are all examined, it is found that the combination of butadiene rubber and the sulfur compound has an unexpected synergistic effect. When combining E and F, the 10% weight loss time at 270 °C is expected to be cumulative, i.e. 235 + 410-645 hours, but there is a surprising synergistic effect, i.e. 785 hours for the B formulation,
795 hours were obtained for the D formulation and 875 hours for the G formulation. A discussion of this synergistic effect will be discussed in more detail later.

Example 3 This example shows the results for materials compounded in a 20-lum mill instead of an extruder. Compound H in this example has the same general composition as B, but the sulfur and rubber were changed as shown, and the phenol content was adjusted to a total of 100 parts in each example depending on the sulfur and rubber. It is an adjustment. The glass fibers were coated with the silane described in Example 1. The entire composition was then dry mixed using a Baderlin-Kelly type blender.

Next, 800 g of the resulting premix 'i was made into bound pieces using a roll mill. Roll temperatures were 100°C and 65°C, and rolling time was 60 seconds. The product was removed from the mill, cooled to room temperature, and then ground through a 3/2 inch sieve. This compound was molded into test samples and tested as in Example 1.

Ml SeiH (roll mill connolandization) powdered acrylonitrinodobutadiene copolymer 6.35 sulfur
0.19 Other glass fiber (178 inches) 35.58 Silane 1,
27 Ethanol (3,00) Stearic acid 0.42 Calcium stearate 0.49 Magnesium oxide 1.17 Clay 29.12 Phenol novolac containing Hexa hardener 25.1
4 Lime 0.27 Total amount (dry) 100.00 The results are shown in the following table.

Properties Volatile content (%) 3.2 Bending strength (9 days 1. Baking treatment) 22,700 Flexural modulus (10'ps 1. Baking treatment) 2.361
0% weight loss time (270° C., hours) 630 50% bending strength loss time (270° C., hours) 66° Although not as good as that of the extruded foam pound B, fairly good heat aging results were obtained. This result shows that the effectiveness of blend modification is not limited to extrusion compounding.

Example 4 Composition F was prepared in the same manner as Composition 0. However, monocarboxylated acrylic rubber latex was used in place of the acrylonitrile-butadiene rubber latex in Formulation C. This acrylic rubber latex is approximately 50% by weight.
It contained a solid content of .

All test samples were prepared and tested in the same manner as in Example 1. The results are shown in the table below.

Other total amount (dry) 100.00 Miyabi' Volatile content (2)) 4.3 Bending strength (pβ1. Baking treatment') 14,700
Flexural modulus (10'ps, t, baking treatment>2.
1910% weight loss time (270℃, hours) 18050
% bending strength loss time (270°C, hours) 165 Acrylate rubber, when evaluated alone,
Acrylate rubber was tested because it generally has better aging resistance than butadiene rubber.

The heat aging of the acrylate rubber-containing phenolic compound was poor, demonstrating that the benefits derived from acrylonitrile-butadiene rubber were unexpected. This was a surprising result since the prior art teaches the use of acrylate rubbers rather than acrylonitrile-butadiene rubbers in thermal stabilization applications.

Example 5 In place of nitrile latex, vinylpyridine-butadiene-styrene latex and carboxylated styrene-butadiene latex were evaluated in Formulation J1. These dung pounds have the same general composition as B, but the sulfur and rubber are varied as indicated, and the phenol content is dependent on the amount of sulfur and rubber, with a total amount of 10
Adjusted so that it was 0 copies.

A test sample was prepared and tested in the same manner as in Example 1. The results are shown in the table below.

1LJL J K Vinylpyridine-butadiene-styrene solid content 6.3
5 0 Carboxylated styrene-butadiene solid content 0
6.35 Sulfur 019 0.19 Other glass fiber (1/8 inch) 35.58 35.58
Silane 1.27 1.27 Ethanol (0,85) (0,85) Stearic acid 0.42 0.42 Calcium stearate 0.49 0.49 Magnesium oxide 1.17 1.17 Clay 29.12 29
．． 12 H@xa curing agent-containing phenol novolac 25.1
4 25.14 Lime 0.27 0.27 Volatile content (%) 4.1 4.3 10% weight loss time (270°C, hours) 550 68
050% bending strength loss time (270°C, hours) 580
650(c) This example shows that other butadiene-containing rubbers used in accordance with the present invention have improved aging life.

The examples were made by varying the formulation, the type of M, N, O all-phenolic resin (novolak vs. resol), the HeXa content, and the zinc oxide used as a curing accelerator. A test sample was prepared and tested in the same manner as in Example 1. The experimental results are shown below.

Phenol resol 0 25.41 0 0Hex
a content 4.08 0 4.05 2.85 Magnesium oxide 1.16 1.16 0 1.16 Zinc oxide 0 0 L770 Powdered acrylonitrile-arrested diene copolymer 6.
35 6.35 6.31 6.35 Sulfur 0.19
0.19 0.19 0.19 Other glass fibers 35.55 35.58 35.33 3
5.58 Silane 1.27 1.27 1.26 1.
27 Ethanol (0,85) (0,85) (0,
84) (0,85) Stearic acid 0.42 0.4
2 0.42 0.42 Calcium stearate 0.
49 0.49 0.48 0.49 Amazukit (dry)
100.00 99.99100.00 99.99
Properties Volatile content (%) 5.4 3.6 3.6 3.8 Bending strength (psi, baking treatment) 18,90023,2
0024,80022.000 song has elastic modulus (10'ps
i, baking treatment) 2.34 2.44 2.45
2.32 10% weight loss time (270℃, hours) 6
35 775 470 75050% bending strength loss time (270'C, hours) 620 720 390 71
0 The excellent aging properties of the present invention can also be obtained with phenol-resol type excreta. It has been found that the use of zinc oxide as a hardening accelerator impairs heat resistance when compared to an equivalent amount of magnesium oxide. Furthermore, it has been found that reducing the Hexa content improves heat resistance. sample,
Both D and P had equal rubber and sulfur contents, but L had a higher moisture content than Di or P (5.
4% versus 3.9% and 3.8%, respectively). Previous experimental results have shown that the higher the moisture content, the faster the aging of phenolic resins.

Example 7 In this example, Formulation P and Cl compounded,
The effect of using tetramethylthiuram disulfide, a sulfur-donating compound, in place of molecular sulfur was investigated. The material components were bound and tested in the same manner as in Example 1. Examples P and Q were compression molded due to mold failure. The preheated preform was transferred once and filled into the female die of the mold. Using similar temperatures,
The molding pressure was 2500 psi (fully indented mold) and the curing time was 3 minutes. Experience has shown that compression molded samples have poorer aging results than transfer molded samples.

The formulations are shown in the table below.

Composition P' Q Powdered acrylonitrile-butadiene copolymer 6
．． 35 6.34 Sulfur 0.19 0 Sulfur as TMTD 0 (0,19)TMTD O
,38 Other glass fiber (1/8 inch) 35.58 35.51
Silane 1.27 1.27 Ethanol (0,85) (0,85) Stearic acid 0.42 0.42 Calcium stearate 0.49 0.49 Magnesium oxide 1.16 1.16 Clay 29.12 29
．． 06 Hexa curing agent-containing phenol novolac 25.0
9 25.04 Lime 0.32 0.32 Total amount (dry) 99.99 99.99 The results are as follows.

Properties (volatile part) 3.8 4.0 Bending strength (psi, baking treatment) 18.500
18.700 Flexural Modulus (10'psi, Baking > 2.19 2.18 10% Weight Loss Time (270
C, time) 510 54550% bending strength loss time (
270°C, hours) 530 565 This example shows that the sulfur donating compound is at least as effective as molecular sulfur in improving aging life. The advantage of this donor over molecular sulfur is that there is less hydrogen sulfide odor during molding of phenolic compounds.

Example 8 In this example, formulations R and S were compounded and the effect of using wollastonite filler instead of clay on an equal volume basis was investigated. Sulfur was added as TMTD. The compounded material was made into a powder and tested in the same manner as in Example 1. The formulation is as follows.

Composition RS Powdered acrylonitrile-butadiene copolymer 6
．． 34 6.11TMTD Toshitenosulfur (0,19
) (0,19) Clay 29.06 0 Wollastonite 0 31.53 TMTD O,380,37 Other glass fiber M (1/8 inch) 35.49 34.26
Silane 1.27 1.22 Ethanol (0,84) (0,82) Stearic acid 0.42 0.41 Calcium stearate 0.51 0.49 Magnesium oxide 1.18 1. ．． 14Hexa Hardener-containing phenolic novolak 25.01 24.14 Lime
0.34 0.33 Water (10,56) (10,20) Total amount (dry) 100.00 100.00 The results are as follows.

Properties Volatile content (average 3.9 3.6 Bending strength (psi, baking treatment) 17,000
21,900 Flexural modulus (106 u1. Baking treatment) 2.06 2.13 10% weight loss time (270℃,
time) 620 46050% bending strength loss time (27
0° C., time > 615 390 From the above data, it can be seen that selecting the appropriate filler is important in optimizing heat aging. Although the wollastonite-filled dung pound was found to have significantly poorer heat aging performance than the hydrated clay-filled material, this formulation aged better than the wollastonite-filled formulation without rubber or sulfur additive gold. It was shown that Thus, from Example 8 it can be seen that the poor heat aging of certain fillers hinders some of the effectiveness of the rubber and/or sulfur components.

Example 9 Compound T-Xi The effects of compounding T-Xi and using it with varying amounts of powdered nitrile rubber, sulfur, and novolac resin were investigated. Samples were prepared and tested as in Example 1 and rFjJ. The dung pound that had reached tB was evaluated as molding properties determined by an orifice flow test, and then subjected to a heat aging test at 270°C. The main formulation changes and corresponding test results are shown below.

From the above data, the molding properties can be adjusted by changing the resin content. As expected, the higher the resin content, the higher the orifice flow and the softer the molded powder. Acrylonitrile-butadiene for aging lifespan
The effect of copolymer rubber substitution content can also be seen. The lower the rubber content, the shorter the aging life. Also, sulfur 'i 0
．． Increasing from 2% to 0.4% provides further benefits in heat aging, especially at low rubber contents. Therefore, a range of performance characteristics can be achieved by varying the proportions of the components.

The effects of the present invention will be explained in further detail with reference to all the drawings.

Figure 1 R (weight loss rate C%) vs. aging time (270°C
) is shown for some of the phenolic molding formulations of the examples above. The following table summarizes the results shown in Figure 1.

10 Control A (Example 1) 155 12 A+0.19% sulfur 235 80 5214
A+6.35% acrylonitrile 390 235 1
52-Butadiene Copolymer From Figure 1 and the table above, the effectiveness of the rubber and sulfur additives against heat aging can be seen from the top of the graph. Sulfur alone improves retention of critical properties by 52%, clothed rubber alone improves retention by 152%, but quite surprisingly, using both in the same formulation improves retention by 416% compared to the control. Ta. This synergistic effect (416%) is what one skilled in the art would expect when using both rubber and sulfur (i.e. 52% + 152% - 204%).
%). These amazing and unexpected effects are
This is a dramatic improvement in the heat aging properties of phenolic molding materials.

FIGS. 2 and 3 illustrate a modified formulation of the present invention, corresponding to both Curve 16 above and Example 10B, compared to a prior art phenolic molding compound. In Figure 2,
Curve 18 is a plastic product with the product name MX-582.
Curve 10' corresponds to the control formulation of Example 1 and Curve 16' corresponds to Formulation B.

In FIG. 2, a heat aging test conducted on a 1/8 x 5 inch bent bar at a temperature of 235° C. is illustrated as a retained weight vs. aging time curve. From this result, curve 16 (formulation B
), it can be seen that the thermal stability of the present invention is well improved. The following table summarizes the results shown in Figure 2.

0 100 100 100 144 97.9 168 98.1 98.7 336 92.1 98.5 341 96.9 408 86.4 98.3 456 95.0 480 75.4 98.1 528 94.2 672 63 .8 96.5 744 90.7 This procedure is the best way to measure the retention of various properties over long periods of time at elevated temperatures. 10% weight loss, 50%
Approximating the flexural strength, the phenolic composition of the present invention, namely Composition B (curve 16'), retains many of its mechanical properties over long periods of testing, and other phenolic materials are similar to the present invention. Compared to this, the properties have deteriorated considerably.

In a separate test at 205°C, samples of Formulation B lost their original weight after a 180 day heat aging test. 96% was retained.

FIG. 3 shows a graph of flexural strength versus aging time for the same composition as in FIG.

That is, 16''l 10' + 18' are formulations A and B, respectively.

It corresponds to MX-582F. Once again, the desirable and advantageous properties of modified formulation B of the invention with both rubber and sulfur additions are demonstrated. Over a period of 180 days, the Formulation B dung pound retained most of its flexural strength, whereas the Control A and MX-582 dung pounds suffered significant flexural strength loss in a much shorter period of time. ing.

As mentioned above, Applicants have determined that elastomers that improve heat aging are those that become brittle with aging, such as butadiene rubber, whereas those that soften with aging (i.e., butyl rubber, natural rubber, acrylate rubber, polyisoprene, etc.) Surprisingly, they found that it does not contribute to the improvement of aging. One possible theoretical interpretation (but not limited to this mechanism) is that rubbers that soften upon high-temperature oxidative aging are due to the fragmentation of polymer chains and the loss of low molecular weight portions (as volatiles) of the fragmented polymer chains. This means that it softens due to losses. This material loss creates voids in the phenolic compound, which effectively add to the voids formed by the deterioration of the phenolic resin. The effect of the voids not only structurally weakens the material, but also creates more rapid oxygen entry channels, ``and increases the oxygen-active surface species on the resin, accelerating heat aging reactions.''

On the other hand, elastomers that become brittle with aging first crosslink due to oxidation, thereby preventing the formation of volatile polymer moieties. In fact, the uptake of oxygen during oxidative deterioration increases the weight and volume of the brittle elastomer, thereby restricting the total passage of oxygen into the phenolic compound containing the dispersed rubber. Example 4 is considered to prove this theory.

[Brief explanation of drawings]

Figure 1 is a logarithmic graph of weight loss (%) versus aging time for some formulations containing the formulations of the present invention; Figure 2 is a graph of weight retention for some formulations containing one of the formulations of the invention. Figure 3 is a graph of flexural strength versus time for several formulations, including one of the formulations of the present invention. Representative Patent Attorney Yoshi 1) Toshio

Claims (1)

[Claims] 1. A thermostable phenol composition comprising a thermosetting phenol resin, a fiber reinforcing material, a rubber composition that becomes brittle when heated, and a thermostable compound selected from the group consisting of a sulfur compound. . 2. The heat-stable phenol composition according to claim 1, wherein the sulfur compound is molecular sulfur or a sulfur-donating compound. 3. A thermostable phenolic composition comprising a thermosetting phenolic resin, a fiber reinforcement, a rubber composition that becomes brittle upon heating, and a sulfur compound. 4. The heat-stable phenol composition according to claim 3, wherein the sulfur compound is a molecular sulfur donor compound.