JP5418157B2 - Polyacetal resin composition and molded article thereof - Google Patents

Description

  The present invention relates to a polyacetal resin composition and a molded body thereof.

  Polyacetal is an aliphatic ether type or a polymer mainly composed of an aliphatic ether, and is mainly derived from methanol, which is a raw material independent of petroleum, and is considered to be a material with a low environmental load. Polyacetal also has high mechanical properties such as rigidity, and is an excellent material used as engineering plastics.

On the other hand, in order to prevent industrial waste from polluting the environment with respect to environmental problems on a global scale in recent years, biodegradable (microbe degradable or natural degradable) materials have attracted attention. Conventionally, it is known that a polymer having an aliphatic ester structure is biodegradable. As a representative example of such a biodegradable polymer, for example, L-lactic acid produced by fermentation And / or polylactic acid (PLA) using D-lactic acid as a main raw material is known. Among these, PLA is also a raw material derived from natural products, and has attracted attention because it reduces CO ₂ emissions.

  For this reason, many disclosures of techniques related to compositions of polyacetal and polylactic acid have been seen (for example, Patent Documents 1 to 3).

  The inventors of the present invention have high compatibility between the polymer having an aliphatic ester structure and polyacetal, and exhibit sufficient biodegradability by reducing the crystallinity of the polyacetal in the obtained resin composition. The present inventors have found a resin composition excellent in mechanical properties (Patent Document 2), and further found that toughness is remarkably improved by using a specific polyacetal (Patent Document 3).

JP 2008-274308 A JP 2000-17153 A JP 2008-038040 A

  However, the compositions described in Patent Documents 1 to 3 are still insufficient in terms of impact resistance and toughness, and further improvements have been expected.

  An object of this invention is to provide the polyacetal resin composition which has the outstanding toughness and impact resistance, and its molded object.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have conducted a polycondensation reaction of a raw material monomer having a polyester structure and a polyester structure in a polyacetal resin composition containing polyacetal (A). The first polymer (B) obtained by the above, and the second polymer (C) consisting of one or more selected from the group consisting of aliphatic polyesters and polyols are blended, and the moles of the aromatic component in the raw material monomer The toughness of the polyacetal resin composition can be adjusted to a predetermined range and the mass ratio of the second polymer (C) to the total of the polyacetal (A) and the first polymer (B) being not more than a certain value. And it discovered that impact resistance was improved notably and came to complete this invention.

That is, the present invention relates to (A) a polyacetal, (B) a first polymer having a polyester structure, which is obtained by a polycondensation reaction of raw material monomers comprising the polyester structure consisting of a dicarboxylic acid and a diol, and (C) an aliphatic polyester. And a second polymer composed of one or more selected from the group consisting of aliphatic polyols, wherein the molar ratio of the aromatic component in the raw material monomer is larger than 0 mol% and not larger than 40 mol%, and polyacetal (A ) and mass ratio of 1 der following second polymer (C) to the total mass of the first polymer (B) is, the der Rukoto more than 100 seconds 1/2 crystallization time of the polyacetal (a) It is the polyacetal resin composition characterized.

  In this case, the toughness and impact resistance can be further improved as compared with the case where the half crystallization time of the polyacetal (A) is less than 100 seconds.

In the said polyacetal resin composition, it is preferable that MVR (Melt Volume Rate) according to ISO1133 of a 1st polymer (B) is 0-100 cm < ³ > / 10 minutes. In this case, excellent in moldability, has the advantage that MVR has excellent mechanical properties (especially toughness) as compared with the case of more than 100 cm ^3/10 min.

  In the polyacetal resin composition, the polyacetal (A) is added with 5.0 to 50 parts by mass of a comonomer with respect to 100 parts by mass of trioxane, trioxane, and one or more cyclic formers other than trioxane and / or Or it is preferable that it is a polyacetal copolymer obtained by copolymerizing with the comonomer which consists of cyclic ether.

  In the polyacetal resin composition, the mass ratio of the polyacetal (A) to the first polymer (B) is preferably 0.1 / 99.9 to 99.9 / 0.1. In this case, a significant effect can be expected compared to the case where the mass ratio is outside the above range.

  Moreover, this invention is a molded object formed by shape | molding the polyacetal resin composition mentioned above. Since this molded article has excellent toughness and impact resistance, various applications requiring excellent toughness and impact resistance, such as injection molded products, extrusion molded products, vacuum / pressure molded products, blow molded products, fibers , Multifilaments, monofilaments, ropes, nets, woven fabrics, knitted fabrics, non-woven fabrics, films, sheets, laminates, containers, foams, fishing lines, fishing nets and the like.

  According to the present invention, a polyacetal resin composition having excellent toughness and impact resistance and a molded article thereof are provided.

  Hereinafter, the polyacetal resin composition of the present invention and the molded product thereof will be described.

[Polyacetal resin composition]
The polyacetal resin composition of the present invention comprises (A) a polyacetal, (B) a first polymer obtained by a polycondensation reaction of a raw material monomer having a polyester structure and a polyester structure comprising a dicarboxylic acid and a diol; And a second polymer containing one or more selected from the group consisting of aliphatic polyesters and polyols. Hereinafter, each component will be described in detail.

(A) Polyacetal The polyacetal in the present invention includes homopolyacetal resin and polyacetal copolymer resin. These can be used alone or in combination.

  Examples of the polyacetal (A) used in the present invention include trioxane consisting of a trimer of formaldehyde, ethylene oxide, epichlorohydrin, 1,3-dioxolane, 1,3,5-trioxepane, 1,3,6-trixocan, An oxymethylene copolymer containing an oxyalkylene unit produced by copolymerization with a comonomer composed of a cyclic ether having 2 to 8 carbon atoms such as glycol formal or diglycol formal is used. Here, the copolymer includes not only a binary copolymer but also a multi-component copolymer. Therefore, as the copolymer, for example, an oxymethylene block copolymer having a block structure other than oxymethylene units and oxyalkylene units, or a polyacetal having a crosslinked or branched structure can be widely used for the acetal copolymer.

  The polyacetal copolymer resin used in the present invention is usually obtained by adding a comonomer composed of one or more cyclic formals and / or cyclic ethers to trioxane and copolymerizing the trioxane and the comonomer. Among them, a polyacetal copolymer resin obtained by adding 5.0 to 50 parts by mass of a comonomer with respect to 100 parts by mass of trioxane upon copolymerization of trioxane and a comonomer is preferable. In this case, the thermal stability is excellent and the affinity with other resins is further improved by lowering the crystallinity as described below. As the polyacetal copolymer resin, a polyacetal copolymer resin obtained by adding 8.0 to 20 parts by mass of a comonomer in the copolymerization of trioxane and a comonomer is more preferable.

  From the viewpoint of improving the affinity with other resins, the polyacetal has a crystallization time of 100 seconds or longer when the polyacetal is held at 200 ° C. for 3 minutes and then cooled at 150 ° C. Preferably, it is 150 seconds or more. However, the ½ crystallization time is preferably 300 seconds or less.

  The polyacetal thus obtained has excellent mechanical properties and at the same time suppresses crystallinity, thereby having an affinity with the aliphatic polymer of the second polymer (C) and the first polymer (B) having a polyester structure. As a result, the toughness and impact resistance of the polyacetal resin composition can be further improved as compared to the case where the crystallization time of polyacetal is less than 100 seconds.

(B) 1st polymer The 1st polymer (B) used for this invention is a polymer containing a polyester structure, The polyester structure is obtained by the polycondensation reaction of the raw material monomer which consists of dicarboxylic acid and diol. It is. The content of the mixture of dicarboxylic acid and diol in the raw material monomer is preferably 100% by mass. Examples of the first polymer include aliphatic dicarboxylic acids having 2 to 9 carbon atoms, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and aliphatic diols having 2 to 9 carbon atoms. Polyester obtained by polycondensation can be used as the main component. As such polyester, for example, Ecoflex (registered trademark) manufactured by BASF, Biomax manufactured by DuPont, and the like are preferably used. Further, the first polymer may further include a polyether structure as long as it includes a polyester structure. As such a first polymer, a thermoplastic polyester elastomer which is a block copolymer of polyester and polyether can be used. Specifically, as such a thermoplastic polyester elastomer, Perprene P-40B manufactured by Toyobo Co., Ltd. can be used. The first polymer may further include a polylactic acid structure as long as it includes a polyester structure. As such a first polymer, a block copolymer of polyester and polylactic acid can be used. Specifically, Ecobio (registered trademark) manufactured by BASF Corporation can be used.

The first polymer preferably MVR measured by the evaluation method in conformity with ISO1133 (Melt Volume Rate) is 0~100cm ^3/10 min. MVR of the first polymer and more preferably from 1 to 20 cm ^3/10 min. In this case, a decrease in the melt viscosity of the entire polyacetal resin composition is prevented, and the impact resistance when dispersed in the polyacetal is further improved.

  In the raw material monomer, the molar ratio of the aromatic component is greater than 0 mol% and 40 mol% or less. When the molar ratio exceeds 40 mol%, the polyacetal is not softened and the toughness is significantly reduced, the glass transition point of the first polymer is 0 ° C. or higher, and the physical property variation at a temperature of room temperature or higher is large. Therefore, the impact resistance is significantly reduced. The molar ratio is more preferably 5 to 30 mol%. The aromatic component means that if the dicarboxylic acid is an aromatic dicarboxylic acid and the diol is an aliphatic diol, the dicarboxylic acid is the aromatic component. In this case, the molar ratio of the dicarboxylic acid in the raw material monomer is the molar ratio of the aromatic component. If the dicarboxylic acid is an aliphatic dicarboxylic acid and the diol is an aromatic diol, the diol is an aromatic component. In this case, the molar ratio of the diol in the raw material monomer is the molar ratio of the aromatic component.

(C) 2nd polymer The 2nd polymer used for this invention contains 1 or more types chosen from the group which consists of aliphatic polyester and a polyol. Examples of the aliphatic polyester include polylactic acid, polycaprolactone, polybutylene succinate, polybutylene succinate adipate, and polyester carbonate. Among them, polylactic acid is preferably used.

  As the polyol, a polyester polyol obtained by polycondensation of a dicarboxylic acid and a diol and having a number average molecular weight of 10,000 or less is used. As the dicarboxylic acid, an aliphatic dicarboxylic acid having a linear or branched structure having 2 to 9 carbon atoms, an aromatic dicarboxylic acid such as terephthalic acid or isophthalic acid, a tricarboxylic acid, or a tetracarboxylic acid may be used. it can. On the other hand, as the diol, a diol having 2 or more carbon atoms, and a linear or branched aliphatic diol is preferably used. Moreover, aromatic diol can also be used as diol.

  As the polyol, polycarbonate diol having a molecular weight of 10,000 or less can be used in the same manner as the polyester polyol. This has a structure in which one or more diols are connected by a carbonate bond. As the diol, an aliphatic diol having a linear or branched structure having 2 to 9 carbon atoms is preferably used. Moreover, aromatic diol can also be used as diol.

In the polyacetal resin composition of the present invention, the following formula:
Mass ratio = M _C / [M _A + M _B ]
(Wherein, _{M A} represents the mass of the polyacetal (A), _{M B} represents the mass of the first Polymer (B), _{M C} represents the mass of the second Polymer (C).)
The mass ratio of the second polymer (C) to the total mass of the polyacetal (A) and the first polymer (B) represented by is 1 or less. When this mass ratio exceeds 1, the toughness and impact resistance are significantly reduced as compared with the case where the mass ratio is 1 or less.

  The mass ratio is preferably 0.8 or less. However, the mass ratio is preferably 0.01 or more from the viewpoint of achieving both high toughness and impact properties.

The weight ratio of the polyacetal (A) for the first Polymer _{(B) (M A / M} B) , the high strength, from the viewpoint of maintaining the rigidity, 0.1 / 99.9 to 99.9 / 0. 1 is preferable, and 40/60 to 99/1 is more preferable.

  The polyacetal resin composition of the present invention can be added with known additives and / or fillers within a range that does not impair the original purpose of the present invention. Examples of additives include crystal nucleating agents, antioxidants, plasticizers, matting agents, foaming agents, lubricants, mold release agents, antistatic agents, ultraviolet absorbers, light stabilizers, heat stabilizers, and deodorants. , Flame retardants, sliding agents, fragrances, antibacterial agents and the like. Examples of the filler include glass fiber, talc, mica, calcium carbonate, potassium titanate whisker and the like. Further, pigments and dyes can be added to achieve a desired color. In addition, transesterification catalysts, various monomers, coupling agents (such as diphenylmethane diisocyanate and its carbodiimide-modified, urethane-modified isocyanates, diaryl carbonates, etc.), end-treatment agents, other resins, wood flour, starch, etc. It is also possible to modify by adding naturally-derived organic fillers.

  In producing the polyacetal resin composition of the present invention, it is preferable to uniformly mix all the components before molding in view of the uniformity, strength, appearance and the like of the resin. You may mix and use for direct shaping | molding. When performing uniform mixing, it can be obtained by mechanical mixing at least at a temperature at which the polyacetal melts. In addition, the polyacetal resin composition of the present invention is a method in which all components are mechanically pulverized, mixed and pressurized, or all components are dissolved in a solvent and then mixed with a poor solvent and precipitated. Can be produced by using a method of producing a polyacetal resin composition of the present invention, or a method of producing a product obtained by casting or spinning a solution in which all components are dissolved in a solvent. The manufacturing method is not limited to them. Although the mixing apparatus of all the components is not specifically limited, The method of mixing using an extruder is industrially recommended at the point which can process continuously in a short time.

  When the mixing temperature is 100 ° C. or lower, the resin has a high melt viscosity or does not melt. Specifically, the range of 100 ° C. to 300 ° C. is preferable. A temperature of 300 ° C. or higher is not preferable because thermal decomposition of the resin occurs. Even when the temperature is 300 ° C. or lower, it is preferable to mix in a short time in a nitrogen atmosphere in order to prevent coloring, deterioration, thermal decomposition, and the like at high temperatures. A specific mixing time of 20 minutes or less is recommended. It is also possible to install a vent port to remove the oligomer, residual monomer, generated gas, etc. in the resin and mix under reduced pressure.

[Molded body]
The molded article of the present invention is an article molded using the polyacetal resin composition of the present invention. Specific molding forms include injection molded articles, blow molded articles, fibers, multifilaments, monofilaments, ropes, and nets. Examples include, but are not limited to, woven fabrics, knitted fabrics, nonwoven fabrics, films, sheets, laminates, containers, foams, fishing lines, and fishing nets. In particular, since the resin composition of the present invention also has excellent toughness, it is excellent in film moldability, filament spinnability, and stretchability as compared with a single product of polyacetal.

  The resulting polyacetal resin composition and molded product thereof have high mechanical properties and a practically sufficient softening temperature, and are expected to be decomposed by microorganisms in soil, activated sludge, and compost. This biodegradability can be adjusted by the molecular weight of the (B) first polymer or (C) second polymer constituting the molded body, the mixing ratio of each component, the thickness of the molded product, and the like.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the examples shown below.

<Examples 1-2, Reference Example 1, Examples 4-5, and Comparative Examples 1-7>
First , as each component of (A), (B) and (C) used in Examples , Reference Examples or Comparative Examples, the following were specifically used.

(A): Acetal copolymer formed by copolymerizing polyacetal (A-1) trioxane and 1,3-dioxolane (comonomer) 1/2 Crystallization time: 100 seconds or more Comonomer amount: 13% by mass (trioxane and comonomer Of the total amount)
Melt index: 9.0 g / 10 min
(A-2) Acetal copolymer obtained by copolymerizing trioxane and 1,3-dioxolane (comonomer) 1/2 Crystallization time: 45 seconds Comonomer amount: 4% by mass (mixing ratio in the total of trioxane and comonomer) )
Melt index: 9.0 g / 10 min

(B) First polymer having a polyester structure (B-1) Ecoflex (registered trademark) manufactured by BASF
Terephthalic acid content at the time of reaction: 20 mol% in all raw material monomers
MVR: 3cm ^3/10 minutes (B-2) manufactured by Toyobo Co., Ltd. PELPRENE P-40B
Terephthalic acid content at the time of reaction: 50 mol% in all raw material monomers
Melt index: 12g / 10min

(C): second polymer comprising aliphatic polyester and / or polyol (C-1) Terramac TP-4000 manufactured by Unitika Ltd.
Melt index: 3 g / 10 min (C-2) Polyester polyol OD-X-2554 manufactured by DIC Corporation
(A polyester polyol formed by copolymerizing adipic acid and 1,4-butanediol, and having a number average molecular weight of about 3000)

In addition, about the melt index and 1/2 crystallization time of the said material, it measured as follows.
(Melt index)
The melt index (MI) was measured under the conditions of a temperature of 190 ° C. and a load of 2.16 kg according to ASTM-D1238.
(1/2 crystallization time)
The ½ crystallization time was measured by performing isothermal crystallization using a Perkin Elmer diamond DSC. Specifically, a 4 mg sample was collected in an aluminum pan, completely melted at 200 ° C. for 3 minutes, immediately cooled to 150 ° C., and the time from which the crystallization exothermic peak appeared was measured.

Table 1 shows the compositions of the polyacetal resin compositions of Examples 1-2, Reference Example 1, Examples 4-5, and Comparative Examples 1-7. The polyacetal resin compositions of Examples 1-2, Reference Example 1, Examples 4-5, and Comparative Examples 1-7 were compounded at a cylinder temperature of 200 ° C. using a twin screw extruder PCM-30 manufactured by Ikegai Co., Ltd. A uniformly mixed pellet was obtained. And the obtained pellet was shape | molded with the injection molding machine, and the molded object was obtained.

  The molded body thus obtained was evaluated for mechanical properties, toughness, bending properties, and impact resistance as follows.

(Mechanical properties)
Mechanical properties were evaluated by conducting a tensile test on the molded body and measuring the tensile strength. At this time, the tensile test specifically shows the tensile strength, the tensile elongation and the tensile modulus when the tensile breaking elongation (between the marked lines) is measured at a tensile test speed of 10 mm / min according to the method of ASTM D638 standard. It was measured. The results are shown in Table 1.

(Toughness)
If the tensile elongation at break was 100% or more, the toughness was accepted as being excellent in toughness, and if the tensile elongation was less than 100%, it was rejected as being inferior in toughness. The results are shown in Table 1.

(Bending characteristics)
The bending characteristics were evaluated by performing a bending test on the molded body. Specifically, the bending test was performed according to ASTM D790 using a test piece of 12.7 mm × 6.4 mm × 150 mm. The results are shown in Table 1.

(Impact resistance)
The impact resistance was evaluated by conducting a tensile impact test and measuring the tensile impact strength. The tensile impact strength was measured according to the method defined in ASTM D1822 using a small tensile test piece having a thickness of 3.2 mm at a room temperature of 23 ° C. Higher values indicate better impact strength. The sample (small tensile test piece) used for the evaluation was prepared by forming a sheet having a thickness of 1 mm with a hot press molding machine at 230 ° C., and after molding, for 24 hours in a temperature-controlled room adjusted to room temperature 23 ° C. and humidity 50%. The condition was adjusted as described above. If the tensile impact strength is 120 kg · cm / cm ² or more, the impact resistance is considered excellent, and if the tensile impact strength is less than 120 kg · cm / cm ² , the impact properties are inferior. It was. The results are shown in Table 1.

As shown in Table 1, the polyacetal resin compositions of Examples 1 and 2, Reference Example 1 and Examples 4 to 5 satisfied both acceptance criteria for toughness and impact resistance. On the other hand, the toughness or impact resistance of the polyacetal resin compositions of Comparative Examples 1 to 7 did not reach the acceptance criteria.

  From this, it was confirmed that the polyacetal resin composition of the present invention is excellent in toughness and impact resistance.

Claims (5)

(A) polyacetal;
(B) a first polymer having a polyester structure and obtained by a polycondensation reaction of raw material monomers comprising the polyester structure consisting of a dicarboxylic acid and a diol;
(C) a second polymer consisting of one or more selected from the group consisting of aliphatic polyesters and aliphatic polyols,
The molar ratio of the aromatic component in the raw material monomer is greater than 0 mol% and 40 mol% or less,
Polyacetal (A) and a second Polymer weight ratio of (C) to the total mass of the first Polymer (B) is Ri der 1 or less,
Polyacetal polyacetal resin composition 1/2 crystallization time, characterized in der Rukoto than 100 seconds (A). The polyacetal resin composition according to claim 1, MVR conforming to ISO1133 of first Polymer (B) is characterized in that it is a 0~100cm ^3/10 min. Polyacetal (A) is added 5.0 to 50 parts by mass of a comonomer with respect to 100 parts by mass of trioxane, and trioxane and a comonomer composed of one or more kinds of cyclic formers and / or cyclic ethers other than trioxane. the polyacetal resin composition according to claim 1 or 2, characterized in that a polyacetal copolymer obtained by copolymerization. The polyacetal resin composition according to any one of claims 1 to 3 , wherein the mass ratio of the polyacetal (A) to the first polymer (B) is 0.1 / 99.9 to 99.9 / 0.1. . The molded object formed by shape | molding the polyacetal resin composition as described in any one of Claims 1-4 .