JPH0723426B2 - Method for producing polyamide-based polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a polyamide-based polymer having excellent impact resistance with almost no decrease in rigidity. In particular, the present invention relates to a method for producing a polyamide-based polymer capable of obtaining a molded product having a good dimensional stability by injection molding or injection molding in which a filler is blended.

“Prior Art” Conventionally, a method for producing a polyamide-based polymer by anionic polymerization of a lactam monomer using a basic catalyst is already widely known, and various molding methods can be performed by this polymerization method. Getting goods is being done.

The polyamide-based polymer obtained by such a polymerization method has a high degree of crystallinity and has various excellent properties such as mechanical strength, wear resistance, and fatigue resistance. Being developed. Unfortunately, however, such a polyamide-based polymer has a drawback that it has poor impact resistance and is not sufficiently satisfactory.

Heretofore, various attempts have been made to improve the impact resistance. For example, JP-B-48-41958, JP-B-49-41354, JP-B-52-15139 and JP-B
54-40118, JP-B 54-40118, JP-57-
17884, JP-A-59-58030, JP-A-59-9613
No. 2 and JP-A No. 59-124930 propose a method of polymerizing a lactam in the presence of a compound having a hydroxyl group at the terminal, for example, a polyalkylene glycol, polylactone or polyol of polyolefin.
However, when these proposed methods are used, it is difficult to control the reaction, and the mold release of the molded product is inferior, and the appearance of the surface of the molded product deteriorates. Not a satisfying method.

Further, a method of producing a polyamide polymer by using a soft segment of a polyol having a modified terminal hydroxyl group as a polymerization initiator has been proposed (JP-A-58).
-21425 gazette). However, in this method, in order to impart impact resistance to the resulting polyamide, a considerably large amount of the above soft segment must be used,
In that case, there is a big drawback that the rigidity is remarkably reduced, and this method is not practically satisfactory.

On the other hand, in recent years, when a molded product is manufactured from a highly reactive liquid raw material such as a combination of a lactam monomer and a basic catalyst, the raw material is injected or injected into a mold to perform polymerization and molding. Attention has been focused on a method of simultaneously performing molding in a mold to directly obtain a molded product, such as a so-called reflection injection molding method or a casting method.

However, in this method, in the case of polymerizing and molding a lactam monomer, in order to impart excellent rigidity and excellent heat resistance to the molded product, a method of compounding a filler is generally used. However, when the filler is mixed with the lactam monomer, it is difficult to uniformly disperse the filler and the monomer because the densities of the two are different, and the presence of the filler in the molded product is uneven. There is a defect that As a result, the linear expansion coefficient is different in various parts, and thus the dimension of the molded product becomes unstable, and a large distortion remains in the obtained product.

[Problems to be Solved by the Invention] The present invention provides a polyamide-based polymer having excellent impact resistance, which is obtained by reacting a lactam monomer with a basic polymerization catalyst, with almost no decrease in rigidity. It is intended to provide a method of manufacturing in time.

Further, the present invention comprises polymerizing a lactam monomer by a so-called reaction injection molding method, a casting molding method, a rotational molding method, a centrifugal molding method, or the like, in which polymerization and molding are performed in a mold to directly obtain a molded product. Accordingly, it is an object of the present invention to provide a method for producing a molded product in which a filler is uniformly dispersed and distortion is small in a short time when a polyamide polymer is produced.

"Means for Solving Problems" Various problems of the conventional method include the following: according to the method of the present invention, a lactam monomer is reacted with a basic polymerization catalyst to produce a polyamide-based polymer. As the initiator, one of the general formulas (I ₁ ) to (I ₄ ), that is, ZO-X'-R ₁ X-A) _α ] _β , ... (I ₁ ) ZO-X'-X-A] _β ... (I ₃ ) and [In these formulas, A is (Wherein Q is an alkylene group having 3 to 11 carbon atoms), α is an integer of 1, 2 or 3, β is an integer of 2 or more, R ₁ is a hydrocarbon group or an ether. A divalent or polyvalent group selected from a hydrocarbon group containing a bond, R ₂ represents hydrogen or a hydrocarbon group, and X and X ′ are Z is (1) minimum molecular weight of about 1000.
And (2) a polyester segment containing a polyether segment having a minimum molecular weight of about 1000 or (3) a hydrocarbon having a minimum molecular weight of 1000. ] A lactam functional substance selected from the group consisting of: and a compound represented by the general formula (II ₁ ) or (II ₂ ) and [In these formulas, A is (Wherein Q is an alkylene group having 3 to 11 carbon atoms), γ is an integer of 1 or more, R ₃ and R ₄ are hydrogen or a hydrocarbon group having 20 or less carbon atoms, and R is ₃ and R ₄ may form a cyclic compound. R ₅ and R ₆ represent hydrogen or a hydrocarbon group having 6 or less carbon atoms, R ₇ represents a hydrocarbon group having 20 or less carbon atoms, and X represents Represents a group selected from ] A polyamide polymer is produced by using at least one compound selected from the group consisting of:

Hereinafter, the present invention will be described in detail.

Examples of the lactam monomer used in the method of the present invention include γ-butyrolactam, δ-valerolactam,
Examples include ε-caprolactam, ω-enanthlactam, ω-capryllactam, ω-undecanolactam, ω-laurinlactam, and these may be used alone or in combination of two or more kinds.

In the method of the present invention, all the basic polymerization catalysts used in the polymerization of lactam monomers can be used as the basic polymerization catalyst. Specific examples thereof include alkali metals, alkaline earth metals, their hydrides, oxides, hydroxides, carbonates, alkyl compounds, aryl compounds, alkoxides, amides, Grignard compounds, and the like, and further with the above metals or metal compounds. There are reaction products with lactams, for example, sodium salt, potassium salt, and magnesium halide salt of ω-lactam. Then,
The amount of these polymerization catalysts to be used is usually in the range of 0.01 to 20 mol% or more based on the total lactam monomer as a raw material.

When producing a polyamide-based polymer by the method of the present invention, in addition to the lactam monomer, the basic polymerization catalyst,
A polymerization initiator is used. The polymerization initiator is a lactam-functional substance represented by the general formulas (I ₁ ) to (I ₄ ) [hereinafter, simply referred to as a compound represented by the general formula (1). ] And a compound represented by the general formula (II ₁ ) to (II ₂ ) [hereinafter, simply referred to as a compound represented by the general formula (II). ] A combination consisting of at least one selected from the group consisting of

Specific examples of the compound represented by the general formula (I) used in the method of the present invention include: Or ₃ [wherein Z represents poly (oxypropylene) having a molecular weight of 6700 or polybutadiene having a molecular weight of 3000], (In the formula, Z is a block copolymer of ethylene oxide and propylene oxide having a molecular weight of 9000,) or (In the formula, Z represents polybutadiene having a molecular weight of 3000) and the like. Further, specific examples of the compound represented by the general formula (II) include: Or And so on.

In the method of the present invention, it is necessary to select and use at least one compound selected from the compound represented by the general formula (I) and the compound represented by the general formula (II) as a polymerization initiator. .

The amount of these compounds used is not particularly limited, for example, when a large amount of the compound represented by the general formula (II) is used, the impact resistance of the resulting polyamide polymer is increased and the reaction rate is also increased. If the amount is too large, a reaction may occur rapidly, resulting in a variation in the thickness of the molded product, which may lower the commercial value. Further, if a large amount of the compound represented by the general formula (II) is used, the cost becomes high and it is not economical.
Therefore, it may be appropriately selected depending on the method of the polymerization reaction, the type of molding method applied, or the degree of elasticity and impact resistance required of the polyamide-based polymer produced.

For example, in the case of producing a polyamide polymer by polymerizing a lactam monomer by reaction injection molding, the flexural modulus of the polyamide polymer molded product immediately after molding is about 20,000 kg.
/ cm ² der connexion, when attempting to impart greater impact resistance to the molded article, .epsilon.-caprolactam with respect to monomer 100 parts by weight, of 27 parts by weight (Z is polybutadiene having a molecular weight of 3000, β is a mixture of 2 and 3) and an acyllactam functional substance and 0.01
Parts by weight Is used as a polymerization initiator, and a basic catalyst may be used in combination for polymerization.

In the method of the present invention, a compound having a polyvalent hydroxyl group, a polyvalent mercapto group, a polyvalent amino group or a polyvalent epoxy group together with a lactam monomer is used as a cross-linking agent, a modifier or a filler. Can be used.

Examples of the compound having a polyvalent hydroxyl group include diethylene glycol, triethylene glycol, tetraethylene glycol, hexylene glycol, 1,2-propanediol, 1,3-butanediol, 1,3-hexanediol, butylene glycol, 1 Alkylene glycols such as 4,4-butanediol, dicyclopentadiene glycol, heptaethylene glycol or isopropylidene bis (p-phenyleneoxypropanol-2), glycerol, pentaerythritol, 1,2,6-hexanetriol or 1 -Polyols such as trimethylolpropane, polyethylene glycol, polypropylene glycol, polyoxypropylene diols and triols, polytetramethylene glycol, castor oil, polybutadiene glycol Lumpur, polyester glycol, and poly (.epsilon.-caprolactone) diol polymeric polyol, and 2,4-dichloro-butylene glycol compounds containing substituents other than hydroxy group, such as such as and the like.

Examples of the compound having a polyvalent mercapto group include hydroxyethyl thioglycolate, ethylene glycol bis (thioglycolate), pentaerythritol tetrakis- (thioglycolate), and thiodiglycol. As the compound having a polyvalent amino group, hexamethylenediamine, tolylenediamine, 2,4
-Diethyl tolylenediamine, polyoxyethylene diamine, polyoxypropylene diamine, polyoxypropylene triamine, copolyamide having an amino group as an end group, and the like.

Examples of the compound having a polyvalent epoxy group include resorcinol diglycidyl ether, diglycidyl ether of bisphenol A, polyglycidyl ester of polycarboxylic acid, epoxidized polyolefin, glycidyl ether resin and epoxy novolak resin.

As the filler, those generally used as a filler for plastics can be used, for example, calcium carbonate, magnesium carbonate, alumina, talc, diatomaceous earth, clay, kaolin, mica, asbestos, glass powder, barium sulfate, burned out. There are Setsukou, silica gel, glass beads, glass balloons, glass flakes, milled glass fibers, cut glass fibers, carbon fibers, carbon whiskers, silicon carbide whiskers, potassium titanate whiskers, wollastonite, etc. It may be surface-treated with a surface-treating agent.

Various methods can be applied to produce a polyamide polymer according to the method of the present invention, for example, a polyamide polymer is obtained as a molded article by reaction injection molding, casting, rotational molding or centrifugal molding. The method can be applied.

In the case of these methods, the raw material is usually prepared by dividing it into a composition of two or more components, and the raw material composition divided into two or more components is subjected to collision mixing at the time of molding and injected into the mold, By carrying out the polymerization and the molding at the same time, the polyamide polymer can be produced as a molded article.

A method for producing a polyamide polymer according to the method of the present invention will be described with reference to an example. That is, first, a polymerization catalyst is put into a lactam monomer and the melting point of the monomer or higher (for example, ε-
In the case of caprolactam, it is heated to 70 ° C or more) to form a melt of one component system (hereinafter referred to as component system A)
Keep below ℃. On the other hand, separately, a lactam monomer, a polymerization initiator comprising a combination selected from the compound represented by the general formula (I) and the compound group represented by the general formula (II) of the present invention, and if necessary, Another component system (hereinafter referred to as component system B) is prepared by adding additives and the like, and this is heated to the melting point of the lactam monomer or higher,
Make a molten material that is kept below ℃.

Further, if necessary, the filler can be added to either one of the component system A and the component system B, or both of the component system A and the component system B, and further, if necessary, substantially. Compounds that do not interfere with the reaction, such as plasticizers,
A foaming agent, a face wash, an antioxidant, an internal mold release agent, or the like may be blended in the component system B and used.

Next, the molten materials of the component system A and the component system B are rapidly mixed and injected or poured into a mold. The mixing method includes, for example, a method of performing collision mixing in a device called a mixing head, a method of stirring and mixing with a static mixer or a dynamic mixer, and the like.

The mixing ratio of the component system A and the component system B is selected according to the application of the polymer to be produced and the properties to be provided, but the mixing ratio is usually in the range of 5/1 to 1/5 by volume. .

When the mold is kept in the range of 100 to 200 ° C., preferably 120 to 160 ° C. after mixing, the reaction is completed by hardening or solidifying within a short period of time, for example, within 4 minutes, and in some cases within 2 minutes. .
After completion of the reaction, the molded product is taken out of the mold to obtain the desired polyamide polymer molded product.

"Effects of the Invention" The present invention has particularly remarkable effects as described below, and its industrial utility value is extremely large.

(1) In the method of the present invention, a polyamide-based polymer having both rigidity and impact resistance is produced in a short time by using two or more specific polymerization initiators. You can

(2) In the method of the present invention, by using at least one polymerization initiator selected from the compound represented by the general formula (I) and the compound represented by the general formula (II), It is possible to obtain such excellent effects, and these effects cannot be obtained by only one kind. Polymer obtained by the use of one type of polymerization initiator,
The rigidity of the molded product cannot be improved.

(3) When the method of the present invention is applied to a method of simultaneously polymerizing and molding in a mold using a filler, the filler having a density difference from that of the liquid raw material is settled or floated in the mold. It is possible to prevent disproportionation caused by the above, and thus it is possible to manufacture a molded product of a polyamide polymer having good dimensional stability and less distortion.

[Examples] Next, the method of the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

In the following examples, the Izod impact value, flexural rigidity and heat generation time of the polyamide polymer were measured, and the warpage was evaluated as follows.

Measurement of Izod impact value: Cut a dry test piece from a flat plate molded product
According to TM D256-73, it measured under the temperature condition of 23 degreeC and -30 degreeC.

Bending rigidity measurement: Cut a dry test piece from a flat plate molded product and
According to TM D790-71, the flexural modulus was measured under the temperature condition of 23 ° C.

Examples 1-2 The following component system A and component system B were prepared in 2,000 cc flasks, respectively, and each was kept at a temperature of 100 ° C.

Component system A ε-caprolactam 944 g Bromomagnesium caprolactam 56 g Component system B ε-caprolactam 537 g Compound represented by general formula (I) [polymerization initiator (C)]
448g (In the formula, Z represents a block copolymer of ethylene oxide and propylene oxide having a molecular weight of about 9,000) (Example 1) or (Example 2) Next, 100 g of each of the component system A and the component system B was placed in a beaker and mixed with a propeller-type stirrer, and the mixture was immediately heated to 140 ° C. by an electric heater to a length of 300 m.
A horizontally placed sheet mold having a cavity of m, width 200 mm, depth 3 mm was poured and held for 4 minutes. The physical properties of the obtained molded product were measured. The results are shown in Table 1.

Comparative Example 1 For comparison, in the method described in Example 1, the component system B
Without using the compound of the general formula [II] of the present application blended in, instead of using ε-caprolactam 15g,
Molding was performed in the same manner as in Example 1, and the physical properties of the resulting molded product were measured. The results are also shown in Table 1.

COMPARATIVE EXAMPLE 2 For comparison, in the method described in Example 1, component system B
Molding was carried out in the same manner as in Example 1 except that 112 g of the polymerization initiator (C) was used instead of the compound of the general formula [II] of the present invention blended in, and the amount of ε-caprolactam was reduced by 97 g. The physical properties of the molded product thus obtained were measured.
The results are also shown in Table 1.

From Table 1, the following is clear.

The polyamide-based polymer obtained by the method of the present invention has both good impact resistance and good bending rigidity as compared with those obtained by the method of Comparative Example.

Claims (1)

[Claims] 1. A method for producing a polyamide polymer by reacting a lactam monomer with a basic polymerization catalyst, wherein the polymerization initiator is represented by the general formula (I ₁ ) to (I ₄ ), that is, ZO-X. ′ -R ₁ X-A) _α ] _β …… (I ₁ ) ZO-X'-X-A] _β ... (I ₃ ) and [In these formulas, A is (Wherein Q is an alkylene group having 3 to 11 carbon atoms), α is an integer of 1, 2 or 3, β is an integer of 2 or more, R ₁ is a hydrocarbon group or an ether. A divalent or polyvalent group selected from a hydrocarbon group containing a bond, R ₂ represents hydrogen or a hydrocarbon group, and X and X ′ are Z is (1) minimum molecular weight of about 1000.
And (2) polyester segments containing polyether segments having a minimum molecular weight of about 1000, or (3) hydrocarbons having a minimum molecular weight of 1000. ] A lactam functional substance selected from the group consisting of: and a compound represented by the general formula (II ₁ ) or (II ₂ ) and [In these formulas, A is (Wherein Q is an alkylene group having 3 to 11 carbon atoms), γ is an integer of 1 or more, R ₃ and R ₄ are hydrogen or a hydrocarbon group having 20 or less carbon atoms, and R is ₃ and R ₄ may form a cyclic compound. R ₅ and R ₆ represent hydrogen or a hydrocarbon group having 6 or less carbon atoms, R ₇ represents a hydrocarbon group having 20 or less carbon atoms, and X represents Represents a group selected from ] A method for producing a polyamide polymer, characterized in that at least one compound selected from the group consisting of: