JPH0678417B2 - Thermoplastic block copolymer - Google Patents

Description

Description: INDUSTRIAL APPLICABILITY: The present invention relates to a novel thermoplastic resin having good tensile strength, wear resistance and flex fatigue resistance in a wide temperature range from low temperature to high temperature while being thermoplastic. It relates to a block copolymer.

Problems to be Solved by the Prior Art and Invention: Polyurethane resin is used as a material having better wear resistance and bending fatigue resistance than before, but normally liquid prepolymer is cast and molded. Inferior in productivity, therefore it is thermoplastic and can easily obtain molded products or films by methods such as injection, extrusion, blow molding, and good tensile strength and wear resistance in a wide temperature range from low temperature to high temperature. It is desired to develop a resin having high elasticity and bending fatigue resistance.

Means for Solving the Problems: As a result of intensive studies to satisfy these demands, the present inventors have found the usefulness of a block copolymer having a specific structure and arrived at the present invention.

That is, the present invention provides (A) a crystalline polyalkylene phthalate having a carboxyl group at the terminal with a number average molecular weight of 300 to 3,000, and (B) an equivalent ratio of polytetramethylene glycol having a number average molecular weight of 300 to 3,000 and a diisocyanate compound ( NCO: O
H) is obtained by reacting the urethane prepolymer having an isocyanate group at the terminal obtained by reacting at a ratio of 2: 1 to 1.6: 1 with an amidation reaction at a substantially stoichiometric ratio,
A thermoplastic block copolymer having a weight average molecular weight of 20,000 to 300,000 in which the crystalline polyester segment is an amide bond and the amorphous polyether segment is a urethane bond.

The crystalline polyalkylene phthalate of the above (A) is used in combination with a para- or meta-substituted aromatic dibasic acid such as terephthalic acid or isophthalic acid, or another dibasic acid or its anhydride within a range not impairing the crystallinity. Neopentyl glycol,
Obtained by reacting a diol having a symmetrical molecular structure such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, dodecanediol, etc. in a proportion in which the carboxyl group of the dibasic acid is in excess of the diol. A typical example is that an aromatic dibasic acid ester such as dimethyl terephthalate is condensed with an excess diol by a transesterification reaction to make all molecular terminals hydroxylated, and then another dibasic acid or dibasic acid is added. It may be reacted with an acid anhydride to convert the molecular end into a carboxyl group. In this case, para or meta substitution of phthalic anhydride, succinic anhydride, adipic acid, sebacic acid, etc. is used within a range that does not impair crystallinity. A dibasic acid other than the aromatic dibasic acid may be used.

Further, terephthalic acid or isophthalic acid may be subjected to ring-opening addition of ethylene oxide or tetrahydrofuran and then esterified with a dibasic acid.

In order to maintain the crystallinity of the crystalline polyalkylene phthalate (A) and to obtain the abrasion resistance of the present invention, the dibasic acid is a total dibasic acid of a para- or meta-substituted aromatic dibasic acid. 70 mol% or more is preferable, and 80 mol%
The above is particularly preferable.

80% by weight or more of the end groups of the crystalline polyalkylene phthalate (A) are preferably carboxyl groups, but the esterification reaction may not be completed and hydroxyl groups may remain.

The molecular weight of the crystalline polyalkylene phthalate of the above (A) is estimated from the measurement of the acid value and the hydroxyl value of the produced resin, and the product resin weight (g) is divided by the sum of the equivalent numbers of the carboxyl group and the hydroxyl group. Is defined as twice the molecular weight, and its molecular weight ranges from 300 to 3000. When the molecular weight is less than 300, the toughness of the resin decreases, and when it is 3000 or more, the abrasion resistance decreases, which is unsuitable, and the range of 500 to 2500 is particularly preferable.

The above-mentioned (B) polytetramethylene glycol is a polyether diol obtained by ring-opening polymerization of tetrahydrofuran, constitutes the amorphous portion of the block copolymer of the present invention, and is particularly resistant to bending fatigue in cold and cold weather. Contribute to the improvement of. The molecular weight of the above-mentioned polytetramethylene glycol (B) is generally 300 to 3000, but is preferably in the range of 400 to 1500.

Examples of the diisocyanate (C) include tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, dicyclohexyl methane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, α, α,
Various diisocyanates such as α ′, α′-tetramethylparaxylylene diisocyanate and α, α, α ′, α′-tetramethylmethaxylylene diisocyanate are used, but hexamethylene diisocyanate is used for applications requiring weather resistance. , Dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, α, α, α ′, α′-tetramethylparaxylylene diisocyanate, α, α, α ′, α′-
Weather resistance can be imparted by using a so-called non-yellowing isocyanate such as tetramethylmethaxylylene diisocyanate. In order to obtain weather resistance and fatigue bending resistance and tensile strength particularly in a wide temperature range, α, α, α ′, α′-tetramethylparaxylylene diisocyanate, which has an aromatic ring and is non-yellowing, α, α , Α ', α'
Most preferably, tetramethylmethaxylylene diisocyanate is used.

The polytetramethylene glycol of the above (B) and the diisocyanate compound of the above (C) are usually reacted by adjusting the isocyanate group of the diisocyanate compound to an excess equivalent ratio to the hydroxyl group of the polytetramethylene glycol and reacting them in advance. A method is used in which a prepolymer having a terminal isocyanate group in which is eliminated is reacted with the crystalline polyalkylene phthalate (A). At this time, the equivalent ratio of the diisocyanate group and the hydroxyl group is preferably in the range of 2: 1 to 2: 1.6, and 2: 1 to 2:
1.3 is particularly preferable because it maintains the tensile strength at high temperature.

The ratio of the terminal isocyanate group prepolymer obtained as described above and the crystalline polyalkylene phthalate of (A) is such that the number of terminal group equivalents of the polyalkylene phthalate is equivalent to the number of isocyanate groups (carboxyl group and residual hydroxyl group). Ratio of 0.95: 1 to 1.0
The reaction is carried out in a weight ratio of 5: 1, more preferably 0.97: 1 to 1.03: 1. If the ratio of the number of equivalents deviates greatly from this range, the molecular weight of the block copolymer produced naturally becomes too small, and the physical strength of the thermoplastic block copolymer obtained decreases.

The above-mentioned (A) crystalline polyalkylene phthalate,
The reaction with the isocyanate prepolymer derived from (B) and (C) is usually above the melting point of the crystalline polyalkylene phthalate, and can be physically stirred and mixed, and thermal decomposition of the resulting copolymer does not easily occur. Temperature, ie normal
It is usually 80 to 160 in the absence of a solvent at a temperature of 130 to 200 ° C. or in an inert organic solvent capable of dissolving polyalkylene phthalate.
The thermoplastic block copolymer of the present invention in a solid state can be reacted at 0 ° C., and then the solvent is removed under reduced pressure or the resulting copolymer is precipitated, precipitated and dried in a solvent that does not dissolve. Can be obtained. This reaction is mainly a decarboxylation reaction of a carboxyl group and an isocyanate group to form an amide bond, while a hydroxyl group partially remaining in (A) the crystalline polyalkylene phthalate reacts with an isocyanate group to generate a urethane. Form a bond. The weight average molecular weight of the obtained thermoplastic copolymer of the present invention is generally in the range of 20,000 to 300,000, and particularly preferably 30,000 to 150,000 in terms of physical properties such as tensile strength and It is preferable from the viewpoint of moldability.

The thermoplastic block copolymer of the present invention obtained as described above has excellent tensile strength, abrasion resistance and bending fatigue resistance in a wide temperature range such as -40 ° C to 80 ° C, and Since it can be molded in the same way as conventional thermoplastic resins such as extrusion molding, injection molding, blow molding, packaging materials,
It can be applied to a wide variety of applications such as tubes, hoses, cords, anti-vibration materials, floor materials, gaskets, tire materials, metal coatings, coating of wire materials such as electric wires and optical fibers, and film-like hot melt adhesives.

Further, in practical use of the thermoplastic block copolymer of the present invention, various fillers such as coloring pigments, extender pigments, reinforcing fibers such as glass fibers and metal fibers, flake conditioners such as glass flakes and mica, and antioxidants. ,
It is possible to mix and use auxiliary agents such as an ultraviolet absorber, a release agent, a lubricant and a plasticizer according to the purpose. It is also possible to use the thermoplastic block copolymer of the present invention in a mixture with other thermoplastic resin, for example, polyvinyl chloride, polyvinylidene chloride-based, polyester-based, polyamide-based or polyurethane-based resin. is there.

The present invention will be specifically described below with reference to examples.

Example Synthesis of crystalline polyalkylene phthalate: Production Example 1 828 parts by weight of bishydroxyethyl terephthalate (addition reaction product of terephthalic acid and ethylene oxide) and 664 isophthalic acid in a reactor equipped with a stirrer, condenser and thermometer. Part by weight was charged, the mixture was heated and melted, the final reaction temperature was raised to 230 ° C., and the reaction was carried out while distilling off the produced water. The time from the start of distilling the produced water to the end of the reaction was 8 hours. The obtained polyalkylene phthalate (A) shows crystallinity, and the acid value and the hydroxyl value were measured.
It contained 1.53 equivalents of carboxyl groups and 0.09 equivalents of hydroxyl groups, and the average molecular weight was estimated to be 1234 from this value.

Production Example 2 830 parts by weight of isophthalic acid were added to the reactor used in Example 1.
472 parts by weight of 1.6-hexanediol was charged, heated and melted, the final reaction temperature was raised to 230 ° C., and the reaction was carried out while distilling off the produced water. The time from the start of distilling the produced water to the end of the reaction was 7 hours. The obtained polyalkylene phthalate (B) shows crystallinity and has 2.19 equivalents of carboxyl groups and 0.48 equivalents of hydroxyl groups per 1000 g of resin from the measurement of acid value and hydroxyl value, and the average molecular weight is estimated from these values. Was 749.

Production Example 3 Dimethyl terephthalate was placed in the reactor used in Example 1.
970 parts by weight and 495 parts by weight of 1.4-butanediol and 2 parts by weight of tetrabutoxytitanium as a catalyst were charged, heated and melted, heated to a final reaction temperature of 220 ° C., and reacted while distilling off generated methanol. . The time from the start of distillation of the produced methanol to the end of the reaction was 6 hours. The equivalent number of hydroxyl groups in 1000 g of the resin was 0.87 equivalent, and the terminal groups were all hydroxyl groups from the dehydration amount of methanol and the result of nuclear magnetic resonance analysis.

Next, 100 parts by weight of succinic anhydride was added and mixed by heating at 140 ° C. for 4 hours, and the disappearance of succinic anhydride was confirmed by an infrared absorption spectrum to obtain a crystalline polyalkylene phthalate (C). From acid value and hydroxyl value measurement, 0.81 in 1000 g of resin
It contained equivalents of carboxyl groups and 0.01 equivalents of hydroxyl groups and had an estimated average molecular weight of 2490.

Production Example 4 In the reactor used in Example 1, 830 parts by weight of isophthalic acid, 146 parts by weight of adipic acid 520 parts by weight of neopentyl glycol and 100 parts of xylene as a solvent for washing sublimated neopentyl glycol from the condenser. Part was charged and melted by heating, the final reaction temperature was raised to 240 ° C., and the reaction was carried out while distilling off the produced water. Finally, the solvent xylene was removed under reduced pressure. The time from the start of dehydration to the end of the reaction was 9 hours. The obtained polyalkylene phthalate (D) shows crystallinity, and from the measurement of acid value / hydroxy value,
It has 1.81 equivalents of carboxyl groups and 0.30 equivalents of hydroxyl groups in 1000 g of resin, and the estimated value of the average molecular weight from this value is
It was 945.

Reaction of polytetramethylene glycol and diisocyanate: Production Example 5 In a reactor equipped with a stirrer, a thermometer, and a condenser, 500 parts by weight of dimethylformamide and 500 parts by weight of diphenylmethane diisocyanate were added, heated and stirred, and reacted at 60 ° C. Keeping the temperature inside the vessel, add 1000 parts by weight of polytetramethylene glycol with a molecular weight of 1000 in 10 portions and add every 15 minutes. After the addition is complete, the reaction is completed by keeping the temperature at 60 ° C for 2 hours and adding 75 parts of isocyanate prepolymer (1). % Solution was made. The isocyanate group content was measured by titration, and it was confirmed to have 1.33 equivalents of isocyanate groups per 1000 g of the solid content.

Production Example 6 In the reactor used in Example 5, 488 parts by weight of α, α,
When α ', α'-tetramethylparaxylisocyanate was charged, it was heated to melt and stirred, and when it reached 130 ° C, polytetramethylene glycol 1500 with a molecular weight of 500
Part by weight is divided into 10 parts and added every 15 minutes.
The reaction was terminated by keeping the temperature at 2 ° C. for 2 hours to obtain an isocyanate polymer (2).

The isocyanate group content was 2.02 equivalents per 1000 g of solid content.

Production Example 7 In the reactor used in Example 5, 439 parts by weight of α, α,
When α ′, α′-tetramethylmethaxylylene diisocyanate was charged and heated to 130 ° C. while stirring, 800 parts by weight of polytetramethylene glycol having a molecular weight of 1000 was added and reacted in the same manner as in Example 6. Was performed to obtain an isocyanate prepolymer (3). The isocyanate group content was 1.11 equivalents per 1000 g of solid content.

Production Example 8 The reactor used in Example 5 was charged with 444 parts by weight of isophorone diisocyanate, and 500 parts by weight of polytetramethylene glycol having a molecular weight of 500 was added in the same manner as in Example 6 when 110 ° C. was reached while heating and stirring. The reaction was carried out by adding by various methods to obtain an isocyanate prepolymer (4). The isocyanate group content was 2.12 equivalents per 1000 g of solid content.

Preparation Comparative Example 1 In the same reactor as in Preparation Example 1, 830 parts by weight of terephthalic acid, 470 parts by weight of 1,4-butanediol, 1 part by weight of dibutyltin oxide as a catalyst, and xylene as a solvent were added.
Part of the mixture was charged, dissolved by heating, and finally the reaction temperature was raised to 230 ° C., water produced was distilled off, and an esterification reaction was carried out for 10 hours. Further, the solvent was removed and the esterification reaction was performed under vacuum at the same temperature for 2 hours to obtain a crystalline polyalkylene phthalate (E). From the measurement of oxidation and hydroxyl number,
The resin had 0.35 equivalents of carboxyl groups and 0.01 equivalents of hydroxyl groups in 1000 g of the resin, and from this value, the estimated average molecular weight was 5650.

Production Comparative Example 2 Outside the same reactor as in Production Example 5, 348 parts by weight of 2,4-toluene diisocyanate was charged and heated to 100 ° C. in a N ₂ stream to add 1,4-butanediol to the system. 94 parts by weight was divided into 3 parts and added every 10 minutes, and after the addition was completed, the reaction was completed at the same temperature for about 3 hours to obtain an isocyanate prepolymer (5).
The isocyanate group content was 4.53 equivalents per 1000 g of prepolymer.

Production of Thermoplastic Block Copolymers: Examples 1 to 10 Polyalkylene phthalates (A) to (D) produced in Examples 1 to 4 and each isocyanate prepolymer produced in Examples 5 to 8 ( 1) to (4) and optionally an organic solvent at a weight ratio shown in Table 1, a stirrer, a thermometer,
A reactor equipped with a condenser was charged, and the reaction was carried out under the temperature and time conditions shown in Table 1 while flowing nitrogen gas. When an organic solvent was used, the organic solvent was distilled off under vacuum to obtain each of the thermoplastic block copolymers (I) to (X). The weight molecular weight of each block copolymer measured by the GPC method is also shown in Table 1.

Comparative Example 1 By using terephthalic acid itself instead of polyalkylene phthalate, an attempt was made to react 100 parts by weight of terephthalic acid with 58 parts by weight of the isocyanate prepolymer obtained in Example 8 in N-methyl stream. Using pyrrolidone solvent 50% together, the reaction was carried out at a reaction temperature of 180 to 220 ° C for 5 hours or more.
The terephthalic acid did not melt sufficiently and the chain length reaction was hardly observed. Above 200 ° C, the thermal decomposition reaction of the isocyanate prepolymer also proceeded, and finally a thermoplastic solid was not obtained.

Comparative Examples 2-3 Polyalkylene phthalate (E) obtained in Production Comparative Example 1
And each of the isocyanate prepolymers (4) or (5) of Production Example 8 and Production Comparative Example 2 were subjected to an amidation reaction in the proportions shown in Comparative Examples (2) to (3) of Table 1, respectively, to obtain a thermoplastic block. A copolymer (XI) (XII) was obtained. The weight average molecular weight determined by GPC is also shown in Table 1.

Evaluation of thermoplastic block copolymer: The thermoplastic block copolymer (I) described in Table 1 ~
Screw diameter of 40m for each of (X) and (XI) to (XII)
Comparative Examples 2 to 3 were 1 at a temperature of 140 to 150 ° C. using an mφ extruder.
Extrusion through a T-die at a temperature of 80-220 ° C and winding through a 50 ° C chill roll yielded a 50μ film.

Table 2 shows the abrasion resistance of the obtained film, the tensile strength at each temperature of −40 ° C., 20 ° C. and 60 ° C., the test result of elongation at break and flex fatigue resistance, and the irradiation test result of the weatherometer.

Claims (1)

[Claims] 1. An equivalence ratio of (A) a crystalline polyalkylene phthalate having a carboxyl group at a terminal with a number average molecular weight of 300 to 3,000, and (B) a polytetramethylene glycol having a number average molecular weight of 300 to 3,000 and a diisocyanate compound. NCO: O
H) a urethane prepolymer having an isocyanate group at the end obtained by reacting at a ratio of 2: 1 to 1.6: 1 is obtained by an amidation reaction at an approximately stoichiometric ratio.
A thermoplastic block copolymer having a weight average molecular weight of 20,000 to 300,000 in which the crystalline polyester segment is an amide bond and the amorphous polyether segment is a urethane bond.