CA1077182A

CA1077182A - Unsaturated epoxy compound-unsaturated silane-filler-polyamide composition and processes therefor

Info

Publication number: CA1077182A
Application number: CA219,616A
Authority: CA
Inventors: Norio Inokuchi; Tomoyoshi Ono
Original assignee: Teijin Ltd
Current assignee: Teijin Ltd
Priority date: 1974-02-09
Filing date: 1975-02-07
Publication date: 1980-05-06
Also published as: DE2505244A1; US3988287A; GB1492643A; DE2505244B2

Abstract

A B S T R A C T
Polyamide compositions comprising a polyamide, an inorganic filler, an unsaturated compound containing an epoxy group, and an unsaturated silane are disclosed, and processes for their preparation. Typically the polyamide is nylon, the filler is clay, quartz, silica, talc or wollastonite, the epoxy compound containing a double bond is a glycidyl derivative, and the silane is a vinyl-methyl or vinyl methoxyethoxy silane. These compositions show improved physical properties over known filled polyamides.

Description

--` 1077182 This invention relates to a polyamide composition, and more specifically, to an inorganic filler to be added to improve the properties of polyamides.
It has been well known to incorporate a fibrous sub-stance such as glass fibers in a polyamide in order to improve its mechanical and thermal properties such as the tensile strength, flexural strength, elasticity modulus, heat distor-tion temperature, dimensional stability, hardness or creep characteristics. According to the recent practice, an inex-pensive inorganic filler, such as clay or talc, `i5 used insteadof the expensive glass fibers to reduce the cost of production.
If, however, these glass fibers or other inorganic fillers are added to polyamides without pretreatment, satisfac-tory properties cannot be obtained because of the poor affinity of the inorganic fillers for the polyamides, and the resulting products are brittle and of low commercial value. In an attempt to remedy such a defect, it has been the practice to pretreat the inorganic filler such as clay, talc, or calcium carbonate with a functional organic group-containing silane compound, chromium compound, surface active agent, or fatty acid polymer solution or latex thereby improving the wetting property or reactivity between the inorganic filler and the resin. Sa-tisfactory results have been obtained with such a treatment when the inorganic filler is a glass fiber, but in the case of such an inorganic filler as clay, talc or calcium carbonate, the adhesion between the treating agent and the inorganic filler and the compatibility of the inorganic filler with the polyamide are insufficient. Thus, no satisfactory effect of reinforcing the polyamide can be obtained.

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~ ~0771~2 This method further has the disadvantage that the procedure oftreating the ;norganic filler with the treating agent is complicated, and the treating agent is expensive or unstable.
Accordingly, it is an object of this invention to provide a polyamide ` composition of improved properties which contains an inorganic filler, and also a process for preparing the polyamide composition.
Extensive investigations in an attempt to achieve the above object led to the discovery that by mixing a polyamide with an inorganic filler and specific compounds, a polyamide composition having superior properties can be very easily obtained.
According to this invention, there is provided in a polyamide composition comprising a polyamide, from 5 to 70 percent by weight, based on the total composition of an inorganic filler selected from the group consisting of talc, clay, mica, silica, quartz, alumina calcium silicate, calcium carbonate, wollastonite, asbestos and carbon black, and a treating agent for improving the compatability of said polyamide and inorganic filler, the improvement comprising a treating agent consisting essentially of from 0.025 to 7 percent by weight, based on the total composition of (a) a compound containing an unsaturated double bond and an epoxy group in one molecule and from 0.015 to 4 percent by weight, based on the total composition of ~b) an unsaturated organic silane of the formula "XSiY3 wherein X is a functional organic group containing at least one unsaturated double bond and Y is a group . hydrolizable to a hydroxyl group" wherein said compound (a) having an unsat-urated double bond and an epoxy group in one molecule and said unsaturated organic silane (b) are present in the heat-polymerized state in the composition.
The present invention also provides a process for preparing the above filler composition which comprises heating a mixture of the compound containing an ~msaturated double bond and an epoxy group in one molecule, the unsaturated organic silane and the inorganic filler to a temperature of at lea~t 30C.
The polyamides used in this invention are not limited in particular, but aliphatic and aromatic polyamides can be used. The aliphatic polyamides . ~ '' 13 ~

.' : . : ~.

10~7182 are especially preferred. Examples of the aliphatic polyamides are nylon-6, nylon-6,6, nylon-6,10, nylon-6,12, nylon-ll and nylon-12. Examples of the aromatic polyamides are poly(hexamethylene diamine terephthalamide), and poly(hexamethylene diamine isophthalamide). They may be used also as mixtures or copolymers with each other.
The inorganic filler includes, for example, talc, clay, mica, silica, quartz, alumina, calcium silicate, calcium carbonate, wollastonite, asbestos, or carbon black. These -3a-~ ~.

~C~';'71132 inorganic fillers may be used either alone or in admixture of two or more. Generally, any inorganic fillers which are in-corporated in thermoplastic or thermosetting resins mainly for the purpose of extending them or improve their hardness, elas-ticity modulus or dimensional stability can be used in this invention.
The amount of the inorganic filler is S to 70% by weight, preferably 20 to 60% by weight based on the total weight of the composition. If the amount is less than 5% by weight, the physical, thermal and chemical properties of the polyamide composition cannot be improved to a satisfactory degree. On the other hand, if it exceeds 70% by weight, shaped articles prepared from the resulting polyamide composition become brittle. In addition, the resulting composition has poor mold-ability, and the surface condition of the shaped articles be-comes poor to degrade their commercial value.
Typical examples of the compound containing a double bond and an epoxy group in one molecule are glycidyl acrylate, glycidyl methacrlate, and glycidyl allyl ether. The amount of this compound is 0.025 to 7% by weight, preferably 0.05 to 6%
by weight, based on the total weight of the composition. If the amount of this compound is less than 0.025% by weight or larger than 7% by weight, the properties of the polyamide com-position are degraded, and the use of a great quantity of this compound is neither preferred by reason of an increased cost of production.
The unsaturated organic silane used in this invention is expressed by the following general formula . ' : ' - ~

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wherein X is a functional organic group containing at least one unsaturated double bond, and Y is a group hydrolizable to a hydroxyl group, such as a halogen, alcohoxy or acetoxy group, and is generally called a silane coupling agent. It is used mainly as a treating agent for plastic-reinforced glass fibers.
Typical examples of the silane are vinyl triethoxysilane, vinyl trimethoxysilane, vinyl tris(~-methoxyethoxy) silane, vinyl trichlorosilane,~-methacryloxypropyl tris( ~methoxyethoxy) silane, and vinyl triacetoxy silane.
The amount of the unsaturated organic silane is 0.015 ; to 4% by weight, preferably 0.025 to 3% by weight, based on the total weight of the composition. Just as in the case of the compound having an unsaturated double bond and an epoxy group in one molecule, good results can neither be obtained if the amount - ~s outside the range specified above.
Various procedures are available to mix the polyamide, the inorganic filler, the compound containing an unsaturated double bond and an epoxy group in one molecule, and the unsa-; 20 turated organic silane. For example, the four ingredients may be blended at a time. In this case, the epoxy compound and the organic silane are considered to penetrate into the interface between the polyamide and the ~norganic filler, and the mixing operation is very easy, too. Alternatively, the inorganic filler ,; 25 are first mixed with the epoxy compound and the organic silane, and then, the mixture is blended with the polyamide. Although this method is more complicated than the first-mentioned method in respect of operation, it has the advantage that almost all of the epoxy compound and the organic silane used are considered ' ' ~.

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~0771B:2 to exist on the interface between the polyamide and the inorganic filler. In this method, the inorganic filler can be treated by mixing it with the epoxy compound and the unsaturated organic silane. This operation is very easy. Also,the inorganic filler can be first mixed with either one of tl-e epoxy compound or the unsaturated organic silane, and then with the other. Since the unsaturated organic silane will first act on the surface of the inorganic filler, it is preferred to mix the inorganic filler first with the unsaturated organic ailane. An organic solvent can be used in this invention in order to ensure an effective contact of these compounds with each other. Preferably, the organic solvent is one which fully dissolves the epoxy compound and the unsaturated organic silane, but does not react with them, and also which wets the inorganic filler well. Examples of preferred organic solvent are ketones such as acetone, or alcohols such as ethyl alcohol or methyl alcohol.
Preferably, the resulting mixture of the inorganic filler, the epoxy compound and the unsaturated organic silane is heated. The heating temperature may vary according to the types or reactivities of the substances, but is usually 30 to 200C., preferably 40 to 180 C.
In order to have the reaction proceed fully and rapidly, a radical polymerization initiator may be added to the above substances. Furthermore, it is preferred to heat the mixture in an atmosphere of an inert gas such as a nitrogen gas in order to prevent undesirable side-reactions.
According to another method, the inorganic filler is mixed first with either one of the epoxy compound or the unsa-turated organic silane, and then with the other of these compound ` 10~7182 and the polyamide. In this method also, a solvent or a catalyst may be used in the treatment of the inorganic filler.
;;` The polyamide composition of this invention prepared above may further contain other additives such as a stabilizer, plasticizer, cross-linking agent, fire-retarding agent, antistatic agent, or thickner. It may also contain a reinforcing agent such as glass fibers.
The physical, thermal and chemical properties of shaped articles prepared from the polyamide composition of this inven-tion are far superior to those of the polyamide itself. Anespecially marked improvement is noted in regard to the flexural strength, elasticity modulus, impact strength, heat distortion temperature, and dimensional stability. In addition, since the inexpensive inorganic filler can be incorporated in great quan-; 15 tities in the expensive polyamides, the polyamide compositions of this invention also offer economical advantages.
The following Examples illustrate the present invention ` in greater detail. In these Examples, all parts are by weight.
The physical properties shown in the Examples were measured by the following methods.
~ (1) Tensile strength and elongation - (2) Flexural strength, elasticity modulus, flex (3) Impact strength (Izod, notched 1/4", 1/8") ;~ ASTM D-256 (4) Rockwell hardness (R scale) - . : - ~ :

loms2 ( r~) Heat distortion temper~ture (~64 psi) ASTM D-64~
(6) Mol~ing shrink~ge A test sp~cim~n, 96 mm x ~ mm x 4 mm in size, molded in a mold at 60C. was allowed to stand for 4~ hours in an atmosphere kept at ~ temperature of 23Co And ~ relative humidity of 6~/~, and then the length of the specimen was measured both in the longitudinal and transverse directions. The molding shrinkage was calculated from the following equationsO
in the lon itudinal = 96 - meas9ur~ed value x 100 direction ~/~ -Molding shrinkage in the tranSV~rse = 85 - measured value x 10 direction (/,) 5 Example l Two parts Or vinyl tris(,~-methoxyethoxy) sil~ne, 4 parts of glycidyl methacrylate and 0012 part of benzoyl peroxide l~ were dissolved in 160 pflrts of acetoneO ~ ~
r- A 100 Parts of calcined clay (~urgess No. 30, a product .
of Burgess Pigment CoO) was mixed with the above solution, and dried fully. The calcined clay so treated was blended with : 150 p~rts of well dried nylon-6 having an intrinsic viscosity of ;~
10~5 using a screw-typ~ extruderO The resulting chips of the nylon composition were molded by an injection molding machine to prepare test pieces. The properties of the test pieces were determined as follows: ;
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Tensile strength ~t break 920 Kg/cm2 Tensile elong.ation at break 6%
Flexural strength 1430 ~g/cm2 Flexural modulus ~6~00 Kg/cm2 Flexural flex lol cm Impact strength ~ inch 6. ~ Kg cm/cm i/8 inch 6.3 Kg cm/cm Rockwell h~rdness (P. scale) 116 Heat distortion temp~rature(264 psi) 121 Molding shrinkage (thickness 4 mm, mol~ temp~rflture 60C.) Iongitudinal direction 10004 ~ransverse direction 1.0~3 E~ample 2 1~ ~wo parts of vinyl tris(j~-methox~rethoxy) silane, 4 parts of glycidyl methacrylate, 0.1 pflrt of t-butyl peroxybenzoate and 0.1 part of dicumyl peroxide were dissolved in 160 parts of acetone.
~o the acetone solution were added 0.1 part of ion exchange water and 0.03 part of glacial acetic acid, and the mixture was thoroughly stirred at room temperature for 30 mi.nutes~ 100 Parts of calcined clay was Dixed with the solution, and then dried sufficientlyO The calcined clay treated was heated in a nitrogen atmosphere for 1 hour at 70Co and then for ; 25 2 hours at 160Co ~ hen, the treated clay was blended with 150 parts of nylon-6 using an extruder, and the resulting composition was molded. ~he properties of the molded articles were determined, _ g _ and are shown in ~able lo Example 3 Two p?rts of vinyl tris-(;3-methoxyethoxy) silane, 4 parts of glycidyl m~thacryl~te and 0.12 part of benzoyl peroxi.de were heated in an atmosphere of nitrogen at 60C. for 1 hourO ~he r~sulting polymer had a molecular weight of 1,2C0 (measured by a vapor pressure osmometer~0 ~he polymer ~.as dissolved in 160 parts of acetone, and 100 parts of calcined clay was addedO After thorough mix-ing, the product was sufficiently dried.
The calcined c]ay so treated was bl~nded with 1~0 parts of nylon-6, and the composition was molded. ~he properties of the molded article were determined, and are shown in ~able lo ComParative Example 1 ::
100 Parts of calcined clay, sufficiently dried but untreated, was blended with 1~0 parts of nylon-~, ?nd the re-sulting composition was molded in th~ same way as in Example 20 The properties of the molded article are sho~ in Table 1. ::
: Comparative Example 2 Example 2 was repeated except that the glycidyl meth-acrylate was not usedO The properties of the molded article are shown in Table lo Comparative Example 3 Example 2 was repeated except that the vinyl tris(~-methoxyethoxy) silane was not used~ The properties of the :. molded article are shown in Table 1 Comparative Exam~le 4 Two parts of ~'-glycidoxypropyl trime-thoxy silane was dissolved in 1~0 parts of acetone, and then 100 parts of calcined .~

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10~711~2 clay was added, followed by thorough drying.
The calcined clay so treated was blended with 150 parts of nylon-6 using an extruder, and molded in the same way as in Example 2. The properties of the molded article are shown in Table 1.
Table 1 I ... T.~n. ile~ -L~ Elexur~r--~
c elon- elasti-Run No. strength gation strength city IImpact at break at break modulus flex Istrength (Kg/cm2) (%) (Kg/cm2) ~(Kg/cm2) (cm) 1l ( Kg cm/cm ~ ... . ... . _ _ .. ., __ . . . . i . . ~ _ ._ ~_ .
Example 2 910 5 1510 1 53700 1.0 1 4.5 Example 3 900 7 1490 ¦ 55100 1.3 ¦ 4.6 Comparative I
Example 1 675 0.8 1240 ¦ 47300 0.6 1 2.8 Comparative Example 2 700 0.9 lZ90 49800 0.7 2.4 Comparative Example 3 680 0.9 1260 50100 0.6 2.6 Comparative Example 4 850 3.5 1350 50000 1.0 3.5 ____ __._ ____.~ .__._ ~ _ ____ _ _ .. ._._ Example 4 Two parts of r-methacryloxypropyltrimethoxy silane,

2 parts of glycidyl methacrylate, 0.08 part of t-butylperoxy benzoate and 0.08 part of dicumyl peroxide were dissolved in 120 parts of acetone. To the solution was added 0.1 part of ion-exchanged water and 0.03 part of glacial acetic acid, and the mixture was stirred at room temperature for 15 minutes.
100 parts of talc (Talc MS, a product of Nippon Talc Co.) was mixed with the above solution, and sufficiently dried.

The talc so treated was sufficiently dried at room ~0~71~32 temperature and atmospheric pressure, and heated at 70 C. for 1 hour, and then at 150C. for 3 hours in a stream of nitrogen.
The talc was then blended with 150 parts of nylon-6 using an extruder, and the composition was molded. The pro-perties of the molded article are shown in Table 2.
Example 5 One part of -methacryloxypropyltrimethoxy silane was added to a solution consisting of 120 parts of deionized water and 0.03 part of glacial acetic acid. The solution was suf-ficiently stirred at room temperature for 30 minutes. Then, 100 parts of wollastonite (F-l*, a product of Interpace Corp.) was added, and after thorough mixing, the mixture was filtered.
After drying at room temperature and atmospheric pressure, the wollastonite so treated was mixed with a solution of 2 parts of glycidyl allyl ether, 0.06 part of t-butyl peroxy-benzoate, and 0.06 part of dicumyl peroxide in 100 parts of acetone, and the mixture was sufficiently dried.
The wollastonite so treated was sufficiently dried at room temperature and atmospheric pressure, and heated in an atmosphere of nitrogen for 2 hours at 70C. and then for 2.5 hours at 160 C. It was then blended with 150 parts of nylon-6 using an extruder, and molded. The properties of the molded article are shown in Table 2.
Example 6 Two parts of vinyltriethoxy silane and 4 parts of glycidyl acrylate were dissolved in 100 parts of acetone, and 100 parts of silica (Crystallite A-l*, a product of Shiraishi Calcium Co.) was added to the solution, followed by thorough mixing.

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:10'771~Z
The silica so treated was blended with 150 parts of nylon-6 using an extruder, and the composition was molded.
The properties of the molded article are shown in Table 2.
Com _ _tive Example 5_ 100 Parts of talc sufficiently dried but not treated was blended with lS0 parts of nylon-6 using an extruder, and the composition was molded in the same way as in Example 4.
The properties of the resulting molded article are shown in Table 2.
Comparative Example 6 100 Parts of wollastonite sufficiently dried but not treated was blended with 150 parts of nylon-6 using an extruder, -and the composition was molded in the same way as in Example 5.
The properties of the resulting molded article are shown in Table 2.
Com~_rative Example 7 100 Parts of silica sufficiently dried but not treated was blended with 150 parts of nylon-6 using an extruder, and the composition was molded in the same way as in Example 6.
The properties of the molded article are shown in Table 2.

10~'71~3~

Table 2 Tensile _ i _ Flexural 'eion- ' ~elasti- ¦ -~
strength ~gation city I Impact Runs at break at break strength modulus ! flex strength (Kg/cm2) (%) I (Kg/cm ) (Kg/cm )I(cm) (Kg.cm/cm ~ _ j _ ~ ~ 1 -.. _ Example 4 840 ; 6 1490 50800 l1.3 4.3 Comparative Example 5 640 0.4 970 48500 0.6 2.6 Example 5 990 5 1600 54000 1.0 5.1 ;

Comparative Example 6 680 0.9 1190 4700 0.8 2.5 Example 6 980 6.1 1580 53900 1.5 4.9 Comparative Example 7 630 0.7 1100 49000 0.8 2.8 ~ ~_ ~ :~
Examples 7 to 10 Two parts of each of the various unsaturated organic silanes shown in Table 3, 4 p&rts of glycidyl methacrylate and 0.12 par-t of benzoyl peroxide were dissolved in 160 parts of acetone, and 100 parts of calcined clay was added to the solu-tion, followed by thorough mixing.
The calcined clay was heated in an atmos-phere of nitrogen at 70 C. for 4 hours. Then, the clay was blended with 150 parts of nylon-6 using an extruder, and the composition was molded. The molded article had the properties shown in Table 3.

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10771~Z

Table 3 . . ~ .. __.__ __ _ ~lexural Type o,r the un- _ _ _ __ _ Runs silane strength modulus f1ex strength _ (k@/cm-) ~kg~cm_) (cm) (Kgo cm/cm~

~xample 7 Vinyl triacetoxy I
~, silane 1~10 r~3600 102 502 ¦ 8 Vinyl trimethoxy silane 1540 51000 1~0 4O9 9 Vinyl trichloro-, silane ¦ 1490 56700 1.4 4.6 I10 ~Y-Meth?cryloxy- l propyl tris(~- , methoxyethoxy) silane 1500 49~00 loO 4.9 .~ _ Examples 11 to 16 ,: _ Two parts of ~'-methacryloxypropyltrimethoxy silane, 4 parts of glycidyl meth~cryl~te and 0012 part of benzoyl per-oxide were dissolved in 160 parts of acetone. 100 Parts of cfllcined clay was mixed with this solution, and dried thoroughly.
The cfllcined clay so treated ?nd nylon-6 were blended with each other in the proportions indicated in T?Able 4 using an extruder. The composition was molded~ The properties of the molded article are shown in Table 4~
The proportion of the calcined clay shown in Table 4 is b?sed on the weight of the clay before the above treatmentO
Comparative Example ~
~ ylon-6 alone WflS ~olded, and the properties of the molded article are shown in Table 4O

10'7'~ Z
Table 4 Blending ~ Flexural _ proport1- s ~
Runs, Nylon-6 rCalcined strength modulus of iImpact ~clay (kg/cm2~ elas-ticity strength I ~ (Kg/cm ) (Kg.cm/cm~
Example 11 90 1 10 1310 33450 4.2 Example 12 80 1 20 1370 38700 4.3 Example 13 70 30 1480 , 47400 4.5 Example 14 60 40 1600 56500 4.9 Example 15 50 50 1790 68300 5.0 Example 16 40 60 1850 79000 4.1 Comparative Example 8 100 _ _ ~_ _1020 23300 3.9 _ Examples 17 to 21 Four parts of vinyl tris(~-methoxyethoxy) silane, 8 parts of glycidyl methacrylate and 0.24 part of benzoyl peroxide were dissolved in 160 parts of acetone. 100 Parts of calcined clay were mixed with the acetone solution, and dried sufficiently.
The calcined clay so treated was heated in an atmosphere of nitrogen at 70 C. for 4 hours. Then, the calcined clay was blended with 100 parts of each of the nylons shown in Table 5 using an extruder, and the composition was molded. The proper-ties of the molded article are shown in Table 5.

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_ Flexurcqï _ Runs ~ype of ~ylon strength¦ mo~ulus Y I I pact . __ ~ . _~K~/c ~ I (K~/cm2) _ (k~.cm~cm~
Example 17 Nylon-6,6 1~00 1 69200 ~!ol Ex~ple lP Nylon-6,10 1100 48600 3.8 Ex~mple 19 Nylon~6,12 900 35000 3.2 Example 20 Nylon-ll 800 30900 1 2-7 ¦
Ex~mple 21 Nylon-12 600 ! 28800 ¦ 3.0 -

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a polyamide composition comprising a polyamide, from 5 to 70 percent by weight, based on the total composition of an inorganic filler selected from the group consisting of talc, clay, mica, silica, quartz, alumina calcium silicate, calcium carbonate, wollastonite, asbestos and carbon black, and a treating agent for improving the compatability of said polyamide and inorganic filler, the improvement comprising a treating agent consisting essentially of from 0.025 to 7 percent by weight, based on the total composition of (a) a compound containing an unsaturated double bond and an epoxy group in one molecule and from 0.015 to 4 percent by weight, based on the total composition of (b) an unsaturated organic silane of the formula wherein X is a functional organic group containing at least one unsaturated double bond and Y is a group hydrolizable to a hydroxyl group" wherein said compound (a) having an unsaturated double bond and an epoxy group in one molecule and said unsaturated organic silane (b) are present in the heat-polymerized state in the composition.

2. The composition of claim 1 wherein said polyamide is selected from the group consisting of nylon-6, nylon-66, nylon-6, 10 nylon-6, 12, nylon-11 and nylon-12.

3. The composition of claim 1 wherein said inorganic filler is selected from the group consisting of clay, silica, talc, quartz and wollastonite.

4. The composition of claim 1 wherein said compound containing an unsaturated double bond and an epoxy group in one molecule is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate and glycidyl allyl ether.

5. The composition of claim 1 wherein said unsaturated organic silane is selected from the group consisting of vinyl triethoxy silane, vinyl tris(.beta.-methoxyethoxy) silane, vinyl trichlorosilane, .gamma.-methacryloxypropyl trimethoxy silane, .gamma.-methacryloxy propyl tris(.beta.-methoxyethoxy) silane and vinyl triacetoxy silane.

6. The composition of claim 1 wherein said polyamide is nylon-6 or nylon-66, said inorganic filler is clay or wollastonite, said compound containing an unsaturated double bond and an epoxy group in one molecule is glycidyl methacrylate, and said unsaturated organic silane is vinyl tris(.beta.-methoxy-ethoxy) silane.

7. The composition of claim 1 wherein said heat-polymerized polymer is one obtained by heat-polymerizing said compound having an unsaturated double bond and an epoxy group in one molecule and said unsaturated organic silane in the presence of a polymerization initiator.

8. A process for preparing the filler composition of claim 1 which comprises heating a mixture of the compound containing an unsaturated double bond and an epoxy group in one molecule, the unsaturated organic silane and the inorganic filler to a temperature of at least 30°C.

9. A process according to claim 8, which comprises heating a mixture of the inorganic filler, the compound containing an unsaturated double bond and an epoxy group in one molecule and the unsaturated organic silane to a temperature of at least 30°C., adding the resulting mixture of the heat-polymerized product and the inorganic filler to the polyamide, and heating the mixture to a temperature higher than the melting point of the polyamide,