JPH032365B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel acetal block copolymer, and more particularly to a method for producing a novel acetal block copolymer having unprecedentedly excellent impact properties and fatigue resistance. Acetal polymers are usually formaldehyde,
It can be obtained by homopolymerizing trioxane or copolymerizing formaldehyde, trioxane, and a cyclic ether. In Japanese Patent Publication No. 41-21638, compounds such as methylal, methanol, formic acid, acetic anhydride, etc.
It is stated that it functions as a chain transfer agent during the polymerization reaction of trioxane. The impact properties of the polymers produced using these compounds are poor. US Pat. No. 3,346,663 describes the polymerization of trioxane in the presence of polyethylene oxide. Also, special public service in 1987-
Public Law No. 38603 also states that trioxane is polymerized in the presence of a copolymer of ethylene oxide and tetrahydrofuran. Further, Japanese Patent Publication No. 17895/1989 discloses a method of copolymerizing trioxane in the presence of a primary polymer such as polyvinyl acetate. The impact properties of the polymers obtained using these methods are all poor, as will be clear from the comparative examples described later, and there is a large room for improvement. The present inventors extensively studied molecular weight regulators to be used during polymerization and found that a certain elastomer functions well as a molecular weight regulator. As a result, we have discovered a new acetal block copolymer that has both excellent impact properties and fatigue resistance, which have not been seen in conventional acetal polymers. That is, the present invention involves homopolymerizing trioxane or combining trioxane and a cyclic ether in the presence of an elastomer having two functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at the terminal end of the polymer. This is a method for producing a novel acetal block copolymer by copolymerization. The present invention will be specifically explained below. In the present invention, at the end of the polymer, a hydroxyl group,
Elastomers having two functional groups selected from the group consisting of carboxyl groups and amino groups are used as molecular weight regulators in the polymerization of trioxane. Here, elastomer is a thermoplastic polymer that is amorphous and has a segment with a low secondary transition temperature (soft segment) and a segment that creates a thermoreversible crosslinked/bonded structure (hard segment).
It is a copolymer with The number average molecular weight (n) of the elastomer is usually
Set between 3000 and 500000. If the molecular weight of the elastomer is too low, the impact properties of the acetal polymer will not be improved sufficiently. On the other hand, if the molecular weight of the elastomer is too high, its function as a molecular weight regulator during the trioxane polymerization reaction is reduced.
From this point of view, in the present invention, 5000~
More preferably, an elastomer with a number average molecular weight of 150,000 is used as the molecular weight modifier. The elastomer functions as a molecular weight regulator during the polymerization reaction of trioxane, and at the same time controls the molecular weight of the polymer, it is also inserted into the polymer as a blocking macromer. The first elastomer that can be used in the present invention
This group includes polystyrene-based elastomers, such as polystyrene-polybutadiene block copolymers (hydroxyl group terminals), hydrogenated polystyrene-polybutadiene block copolymers (hydroxyl group terminals), and hydrogenated polystyrene-polyisoprene block copolymers (hydroxyl group terminals). The second group is polyester elastomers, such as polyethylene terephthalate.
Polypropylene glycol block copolymer (hydroxyl group, carboxyl group terminal), polybutylene terephthalate-polytetramethylene glycol block copolymer (hydroxyl group terminal), polyethylene butylene terephthalate-polytetramethylene glycol block copolymer (hydroxyl group, carboxyl group terminal), bis(β- Examples include elastomers (hydroxyl group, carboxyl group terminal) synthesized from hydroxyl ethyl) terephthalate, terephthalic acid, and polytetramethylene glycol. The third group is polyamide-based elastomers, such as nylon-6-polypropylene glycol block copolymer (terminated with amino groups and carboxyl groups), nylon-6-polyethylene adipate block copolymer (terminated with carboxyl groups), and nylon-6,6-polyethylene glycol block copolymer (terminated with carboxyl groups). Examples include polybutylene succinate block copolymers (terminated with amino groups), nylon-6-polytetramethylene glycol block copolymers (terminated with hydroxyl groups and amino groups), and nylon-12-polypropylene glycol block copolymers (terminated with carboxyl groups and amino groups). The fourth group is polyurethane elastomers, such as polyurethane synthesized from 4,4'-diphenylmethane diisocyanate, tetramethylene glycol, and polytetramethylene glycol (hydroxyl group, amino group terminal), 4,4'-dicyclohexyl Examples include polyurethane (hydroxyl group, amino group terminal) synthesized from methane diisocyanate, propylene glycol, and polypropylene glycol. In addition to these four groups, elastomers having two hydroxyl groups, carboxyl groups, and two amino groups at the polymer terminals can of course be used in the present invention. Prior to polymerization, elastomers are washed, adsorbed,
It is preferable that it be purified by methods such as drying.
Further, these elastomers can be used alone, or two or more kinds can be mixed and subjected to polymerization. In the polymerization of the present invention, sufficiently purified trioxane and cyclic ether are used as starting materials for the acetal block copolymer. The first group of cyclic ethers has the general formula

[Formula] (R ₀ : selected from hydrogen alkyl group, aryl group,
They may be the same or different. m=2
There are alkylene oxides represented by ~6).
For example, ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin, styrene oxide, oxetane, 3,3-bis(chloromethyl)oxetane, tetrahydrofuran,
There are oxepane etc. Among these alkylene oxides, ethylene oxide is particularly preferred. The second group of cyclic ethers has the general formula

There is a cyclic formal that can be expressed by [Formula]. For example, ethylene glycol formal, propylene glycol formal, diethylene glycol formal, triethylene glycol formal, 1,4
-butanediol formal, 1,5-pentanediol formal, and 1,6-hexanediol formal. Among these cyclic formals, ethylene glycol formal, diethylene glycol formal and 1,4-butanediol formal are particularly preferred. The cyclic ether is 0.03 to 100 parts by weight, more preferably 0.1 to 100 parts by weight, based on 100 parts by weight of trioxane.
50 parts by weight are used. A cationic polymerization catalyst is used in the homopolymerization and copolymerization of trioxane of the present invention. Cationic polymerization catalysts include tin tetrachloride, tin tetrabromide, titanium tetrachloride, aluminum trichloride, zinc chloride, vanadium trichloride, antimony pentafluoride, boron trifluoride, boron trifluoride diethyl etherate,
So-called Friedel-Crafts type compounds such as boron trifluoride coordination compounds such as boron trifluoride acetic anhydrate and boron trifluoride triethylamine complex compounds, perchloric acid, acetyl perchlorate, hydroxyacetic acid, trichloroacetic acid, Inorganic and organic acids such as p-toluenesulfonic acid, complex salt compounds such as triethyloxonium tetrafluoroborate, triphenylmethylhexafluoroantimonate, allyldiazonium hexafluorophosphate, allyldiazonium tetrafluoroborate, diethylzinc, triethyl aluminum,
Examples include alkyl metals such as diethylaluminum chloride. These cationic polymerization catalysts are trioxane
It is used in a range of 0.0005 to 5 parts by weight per 100 parts by weight. Polymerization is carried out without a solvent or in an organic medium. Organic media that can be used in the present invention include aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, cyclohexane, and cyclopentane, benzene, toluene,
Examples include aromatic hydrocarbons such as xylene, halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, and trichloroethylene, and halogenated aromatic hydrocarbons such as chlorobenzene and o-dichlorobenzene. These organic media may be used alone or in combination of two or more. The elastomer, which is a molecular weight regulator, is used after being uniformly dissolved or dispersed in the polymerization system. The concentration of the molecular weight regulator in the system can be easily determined by experiment, depending on the molecular weight requirements of the desired acetal block copolymer. The polymerization temperature is usually set between -20 and 150°C, more preferably 55 to 140°C in the case of no solvent, and more preferably 20 to 120°C in the case of using an organic medium. There are no particular restrictions on the polymerization time, but it is usually set between 5 seconds and 300 minutes. After a predetermined period of time has elapsed, a terminator is added to the reaction system to complete the polymerization. The obtained polymer is stabilized by removing unstable ends by hydrolysis or blocking unstable ends by a method such as esterification. The stabilized acetal block copolymer is put into practical use with the addition of a stabilizer and the like. The features of the process for producing the acetal block copolymer of the present invention, which have been described in detail above, are listed below. (1) The acetal block copolymer has extremely excellent impact properties and hydroxyl group resistance. (2) By using a specific elastomer, it is possible to impart excellent performance to the acetal block copolymer, and at the same time, the molecular weight of the polymer can be controlled arbitrarily. Measurement items in the following examples are as follows. MI: 2,2-methylene-bis(4-
methyl-6-tert-butylphenol) 0.25 parts,
0.50 parts of nylon 6-6 was added and pelletized using a 50 mmφ extruder. The MI of this pellet is
Measured according to ASTM-D1238-57T, MI is a measure of molecular weight. Izot impact value (notched): The above pellet was molded into a flat plate using an injection molding machine. A test piece was cut from this flat plate and measured according to ASTM-D256. The larger the Izot impact value, the better the impact properties. Vibration fatigue characteristics: Cut a test piece from a flat plate,
Measured at 20°C and repeated vibration cycles of 1800 times/min in accordance with ASTM-D671. 10 The maximum stress that does not cause the specimen to break when subjected to repeated vibrations ⁶ times = fatigue strength is used as an index of fatigue resistance. The higher the fatigue strength, the better the fatigue resistance. Example 1 500 parts of sufficiently purified trioxane (hereinafter, parts indicate parts by weight), 10 parts of ethylene oxide, and polybutylene terephthalate-polytetramethylene glycol block as a molecular weight regulator were placed in a kneader having two Σ-type stirring blades. 120 parts of a copolymer (hydroxyl group terminal, n=3×10 ⁴ , hereinafter abbreviated as PBT-PTG) was charged and heated to 70°C. Next, 0.35 part of boron trifluoride dibutyl etherate was added to the kneader, and the mixture was stirred for 35 minutes. After 35 minutes,
15 parts of tributylamine were added to stop the polymerization. The contents were taken out from the kneader and thoroughly washed with hot chloroform. This washing removes any unreacted
PBT-PTG is removed. Next, vacuum drying was performed to obtain 523 parts of an acetal block copolymer. The physical properties of this polymer were as follows. MI 9.2 (g/10 minutes) Izot impact value 21.7 (Kg・cm/cm) Fatigue strength 275 (Kg/cm ² ) This polymer has the desired molecular weight and has excellent impact properties and fatigue resistance. have. Examples 2 to 14 The same reagents as in Example 1 were used, except that the starting materials and elastomers listed in Table 1 were used in place of the starting materials and elastomers used in Example 1, and the same procedure as in Example 1 was carried out. operated. The obtained results are also shown in Table 1. In each of the examples, acetal block copolymers having the desired molecular weight and excellent impact properties and fatigue resistance were obtained. Comparative Examples 1 to 3 Instead of the elastomer used in Example 1, the first
Example 1 except that the polymers listed in the table were used.
The same procedure as in Example 1 was carried out using the same reagents.
The obtained results are also shown in Table 1. In all comparative examples, it was difficult to control the molecular weight;
Also, the impact properties of the polymer were poor.

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Claims (1)

[Claims] 1. A method characterized by homopolymerizing trioxane in the presence of an elastomer having two functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at the terminal end of the polymer. A new method for producing acetal block copolymers. 2. A novel method characterized by copolymerizing trioxane and a cyclic ether in the presence of an elastomer having two functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, and an amino group at the end of the polymer. Method for producing acetal block copolymer. 3 The number average molecular weight of the elastomer is 3000~
500,000, the manufacturing method according to claims 1 and 2. 4. The production method according to claim 2, wherein the cyclic ether is ethylene oxide. 5 The cyclic ether is ethylene glycol formal, diethylene glycol formal and 1,
The method according to claim 2, wherein the compound is selected from the group consisting of 4-butanediol formal.