JP2005120119A - Flame-retardant injection-molded body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart excellent flame retardancy together with durability to an injection-molded body comprising a biodegradable plastic having incorporated a metal hydroxide as a flame-retardant. <P>SOLUTION: The flame-retardant injection-molded body has a composition comprising a resin composition (A) mainly composed of a lactic acid-based resin, a metal hydroxide (B) having its surface treated with a silane coupling agent and an aromatic carbodiimide (C). The surface treatment of the metal hydroxide as the flame-retardant with the silane coupling agent in combination with the incorporation of the aromatic carbodiimide (C) permits acquisition of the injection-molded body satisfying both excellent flame retardancy and durability. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection-molded article containing a lactic acid resin as a main component, and more particularly to an injection-molded article having flame retardancy.

  Plastics are now pervasive in every field of life and industry, with annual production of around 100 million tons worldwide. However, most of them are discarded after use, and this is recognized as one of the causes that disturb the global environment. Therefore, effective use of exhaustible resources has become important in recent years, and the use of renewable resources has become an important issue.

  Currently, one of the means attracting attention as a solution is the use of plant raw material (biodegradable) plastic. Plant-based plastics are notable for not only using non-depleted resources and saving exhaustible resources during plastic production, but also having excellent recyclability. Among them, lactic acid-based resins, in particular, can be mass-produced by chemical engineering using lactic acid obtained by fermentation of starch as a raw material, and are excellent in transparency, rigidity, heat resistance, etc. As an alternative material, it has attracted attention in the field of injection molding for home appliances, OA equipment, automobile parts and the like.

  By the way, in applications such as home appliances, OA equipment, and automobile parts, flame retardance for fire prevention is required. However, since lactic acid-based resins are easily flammable resins such as polystyrene and ABS, these It is necessary to take flame retardant measures such as blending a flame retardant when used in the above applications.

  Conventionally, in the case of polystyrene, ABS, and the like, flame retardant measures are often taken by incorporating a halogen-based flame retardant, particularly bromine-based flame retardant. There is a risk of generating harmful gases, and there has been a problem in terms of safety during waste incineration and thermal recycling.

From this point of view, “metal hydroxide” is attracting attention as an environmentally friendly flame retardant that does not generate cracked gas.
For example, Patent Document 1 discloses a method for imparting flame retardancy by blending aluminum hydroxide or magnesium hydroxide in an amount of 30 to 50 wt% into pellets made of a biodegradable plastic raw material.
JP-A-8-252823

  However, when a metal hydroxide is mixed with a biodegradable plastic to produce an injection-molded product, the decomposition of the biodegradable plastic is accelerated by alkali ions in the flame retardant during resin kneading, resulting in a decrease in molecular weight and mechanical strength. It has been found that it occurs. In addition, when metal hydroxide is used as a flame retardant, it has been found that it is particularly difficult to avoid a decrease in mechanical strength because a large amount of metal hydroxide needs to be blended.

  Accordingly, the present invention is an injection molded article obtained by blending metal hydroxide with a biodegradable plastic as a flame retardant, and does not provide a flame retardant injection molded article having excellent flame retardancy and durability. It is what.

As a result of intensive studies in view of such a current situation, the present inventors have completed the present invention with high effects.
The present invention contains a resin composition (A) containing a lactic acid resin as a main component, a metal hydroxide (B) surface-treated with a silane coupling agent, and an aromatic carbodiimide (C). We propose a flame-retardant injection molded article having the composition

The surface of the metal hydroxide blended as a flame retardant is treated with a silane coupling agent, and an aromatic carbodiimide (C) is blended to obtain an injection molded article having excellent flame retardancy and durability. Can do.
At this time, if an aliphatic carbodiimide is blended instead of the aromatic carbodiimide (C), it is difficult to obtain the desired durability. The reason is probably that aliphatic carbodiimide is more reactive than aromatic carbodiimide, and the functional group that affects durability disappears due to the reaction during molding.

  The present invention further proposes that an ester compound having a molecular weight of 200 to 1000 is blended with the resin composition (A). By blending an ester compound having a molecular weight of 200 to 1000, the impact resistance of the injection molded product can be enhanced.

The present invention further proposes that a crystallization accelerator is blended with the resin composition (A) and crystallization treatment is performed at the time of injection molding.
In order to improve the heat resistance of the injection-molded product, it is preferable to perform crystallization treatment. However, in the case of a resin composition containing a lactic acid resin as a main component, the crystallization speed is very slow. Is preferably blended to shorten the crystallization time.

In the present invention, the “resin composition containing a lactic acid resin as a main component” means a resin composition containing a lactic acid resin in an amount of 50 to 100% by mass, particularly 70 to 100% by mass. It is.
The upper limit value and the lower limit value of the numerical range in the present invention are included in the scope of the present invention as long as they have the same operational effects as those in the numerical range, even when slightly deviating from the numerical range specified by the present invention. It is intended to include

  Embodiments of the present invention will be described below, but the scope of the present invention is not limited to the embodiments described below.

  A flame-retardant injection-molded article according to an embodiment of the present invention includes a resin composition (A) containing a lactic acid resin as a main component, and a metal hydroxide (B) surface-treated with a silane coupling agent. Can be obtained by blending an aromatic carbodiimide (C) with a resin composition containing the above and injection molding it.

(Resin composition)
The resin composition, which is a constituent component of the injection-molded article of the present invention, is mainly composed of a lactic acid resin, and if necessary, other resin components having biodegradability are blended (polymer blend). It may be.

[Lactic acid resin]
The lactic acid-based resin used in the present invention includes poly (L-lactic acid) whose structural unit is L-lactic acid, poly (D-lactic acid) whose structural unit is D-lactic acid, or structural units whose L-lactic acid and D are structural units. -Poly (DL-lactic acid) which is lactic acid, or a mixture of two or more of these can be used. At this time, the DL composition ratio of the lactic acid-based resin is preferably L-form: D-form = 100: 0 to 90:10, or L-form: D-form = 0: 100 to 10:90. Preferably, L-form: D-form = 99.5: 0.5 to 94: 6, or L-form: D-form = 0.5: 99.5 to 6:94. Within such a range, heat resistance can be easily obtained and can be used for a wide range of applications.

In addition, the lactic acid resin used in the present invention may be a copolymer of any of the above lactic acids and an α-hydroxycarboxylic acid, an aliphatic diol, or an aliphatic dicarboxylic acid.
At this time, as the “α-hydroxycarboxylic acid” copolymerized with the lactic acid resin, optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), Glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyn-butyric acid, 2-hydroxy3,3-dimethylbutyric acid, 2-hydroxy-3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, etc. Examples of the “aliphatic diol” that is copolymerized with a lactic acid resin include ethylene glycol, 1,4-butanediol, 1 and lactones such as bifunctional aliphatic hydroxy-carboxylic acid, caprolactone, butyrolactone, and valerolactone. , 4-cyclohexanedimethanol and the like, and “aliphatic dicarboxylic acid” includes succinic acid, adipic acid, suberic acid, sebacic acid and dodeic acid. Down two acid and the like.

As a polymerization method for the lactic acid-based resin, a condensation polymerization method, a ring-opening polymerization method, and other known polymerization methods can be employed. For example, in the condensation polymerization method, L-lactic acid or D-lactic acid, or a mixture thereof can be directly dehydrated and condensation polymerized to obtain a lactic acid resin having an arbitrary composition.
Further, in the ring-opening polymerization method, a polylactic acid-based polymer can be obtained using lactide, which is a cyclic dimer of lactic acid, using a selected catalyst while using a polymerization regulator or the like as necessary. At this time, L-lactide which is a dimer of L-lactic acid, D-lactide which is a dimer of D-lactic acid, or DL-lactide composed of L-lactic acid and D-lactic acid is used as the lactide. It is possible to obtain a lactic acid resin having an arbitrary composition and crystallinity by mixing and polymerizing these as necessary.

It should be noted that the lactic acid resin used in the present invention may be a non-aliphatic dicarboxylic acid such as terephthalic acid or an ethylene oxide adduct of bisphenol A as a small amount of a copolymer component as required for improving heat resistance. Non-aliphatic diols may be added.
Furthermore, a small amount of a chain extender such as a diisocyanate compound, an epoxy compound, or an acid anhydride may be added for the purpose of increasing the molecular weight.

The preferred range of the weight average molecular weight of the lactic acid resin used in the present invention is 50,000 to 400,000, more preferably 100,000 to 250,000. If the molecular weight is 50,000 or more, suitable practical physical properties can be expected, and if it is 400,000 or less, there is no problem that the melt viscosity is too high and the molding processability is inferior.
Typical examples of the lactic acid resin include the Laissia series made by Mitsui Chemicals, and the Nature Works series made by Cargill Dow.

[Resin components other than lactic acid resins]
As described above, the resin composition forming the injection-molded article of the present invention has an aliphatic polyester having biodegradability, an aromatic polyester having biodegradability, or biodegradability as necessary. Aromatic aliphatic polyester can be blended (polymer blend).

[Aliphatic polyester with biodegradability]
Examples of aliphatic polyesters having biodegradability other than lactic acid resins include aliphatic polyesters obtained by condensing aliphatic diols and aliphatic dicarboxylic acids, and aliphatic polyesters obtained by ring-opening polymerization of cyclic lactones. Group polyester, synthetic aliphatic polyester, and the like.

The above “aliphatic polyester obtained by condensing an aliphatic diol and an aliphatic dicarboxylic acid” includes any one of ethylene glycol, propylene glycol, 1,4-butanediol and 1,4-cyclohexanedimethanol, which are aliphatic diols. Or a mixture of two or more of these, and aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, sebacic acid and dodecanedioic acid, or two or more of these Aliphatic polyesters obtained by condensation polymerization with a mixture of combinations can be used. If necessary, a polymer obtained by jumping up with an isocyanate compound or the like can also be used.
The preferable range of the weight average molecular weight of the aliphatic polyester is 50,000 to 400,000, more preferably 100,000 to 250,000.
Specific examples include Bionole series manufactured by Showa Polymer Co., Ltd. and Enpole manufactured by Ile Chemical Co., Ltd.

  The aliphatic polyester, that is, an aliphatic polyester obtained by condensing the aliphatic diol and the aliphatic dicarboxylic acid, and a copolymer obtained by transesterifying a lactic acid resin can also be used. The copolymer thus obtained can also be adjusted to a predetermined molecular weight using an isocyanate compound or a carboxylic acid anhydride.

The “aliphatic polyester obtained by ring-opening polymerization of cyclic lactones” includes any of cyclic monomers such as ε-caprolactone, δ-valerolactone, β-methyl-δ-valerolactone, or two or more of them. What polymerized the component which consists of these can be used.
The preferable range of the weight average molecular weight of the aliphatic polyester is 50,000 to 400,000, more preferably 100,000 to 250,000.
As a specific example, a cell green series manufactured by Daicel Chemical Industries, Ltd. can be mentioned.

As the “synthetic aliphatic polyester”, cyclic acid anhydrides and oxiranes, for example, copolymers of succinic anhydride with ethylene oxide, propylene oxide and the like can be used.
The preferable range of the weight average molecular weight of the aliphatic polyester is 50,000 to 400,000, more preferably 100,000 to 250,000.

[Aromatic polyester with biodegradability]
Examples of the aromatic polyester having biodegradability include biodegradable aromatic aliphatic polyesters composed of an aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, and an aliphatic diol component.

  In this case, examples of the “aromatic dicarboxylic acid component” include isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid. Examples of the aliphatic dicarboxylic acid component include succinic acid, adipic acid, and suberin. Examples of the “aliphatic diol” include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and the like. Two or more types of aromatic dicarboxylic acid components, aliphatic dicarboxylic acid components, or aliphatic diol components can be used.

  In the present invention, the aromatic dicarboxylic acid component most preferably used is terephthalic acid, the aliphatic dicarboxylic acid component is adipic acid, and the aliphatic diol component is 1,4-butanediol.

[Aromatic aliphatic polyester with biodegradability]
Examples of the aromatic aliphatic polyester having biodegradability include biodegradable aromatic aliphatic polyesters composed of an aromatic dicarboxylic acid component, an aliphatic dicarboxylic acid component, and an aliphatic diol component.
Examples of the aromatic dicarboxylic acid component include isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid. Examples of the aliphatic dicarboxylic acid component include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanoic acid. Examples of the aliphatic diol include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and the like. Two or more types of aromatic dicarboxylic acid components, aliphatic dicarboxylic acid components, and aliphatic diol components can be used.
Among the above, the aromatic dicarboxylic acid component that can be most suitably used is terephthalic acid, the aliphatic dicarboxylic acid component is adipic acid, and the aliphatic diol component is 1,4-butanediol.
Typical examples of the aromatic aliphatic polyester include a copolymer of polybutylene adipate and terephthalate (Ecoflex manufactured by BASF) and a copolymer of tetramethylene adipate and terephthalate (Eastman Bio manufactured by Eastman Chemicals).

  In addition, it is preferable that the glass transition temperature (Tg) of said aliphatic polyester, aromatic polyester, and aromatic aliphatic polyester is 0 degreeC or less from the impact-resistant improvement effect.

(Metal hydroxide)
It is important that the metal hydroxide (hydrated metal compound) used in the present invention is subjected to surface treatment with a silane coupling agent.
By treating the surface of the hydroxide with a silane coupling agent, reducing the number of blended parts by improving flame retardancy (that is, suppressing deterioration of mechanical properties), and when kneading with a resin or injection molding It is possible to suppress a decrease in molecular weight during molding.

  Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, calcium / aluminate hydrate, tin oxide hydrate, and progobite. Among these, aluminum hydroxide is particularly preferable in terms of flame retardancy and cost.

Examples of the silane coupling agent include epoxy silane, vinyl silane, methacryl silane, amino silane, isocyanate silane, and the like, and it is particularly preferable to use epoxy silane.
For example, titanate coupling agents, higher fatty acids and the like other than silane coupling agents have poor adhesion to the resin, making it difficult to develop flame retardancy.

  Moreover, in addition to said hydrated metal compound, a flame-retardant adjuvant can be mix | blended and a flame-retardant efficiency can be improved further. Specific examples of flame retardant aids include metal compounds such as zinc stannate, zinc borate, iron nitrate, copper nitrate, sulfonate metal salts, phosphorus compounds such as red phosphorus, high molecular weight phosphate esters, and phosphazene compounds. And nitrogen compounds such as melamine cyanurate, or silicone compounds such as dimethyl silicone, phenyl silicone, and fluorine silicone.

(Aromatic carbodiimide)
In the injection-molded article of the present invention, in order to impart hydrolysis resistance, 0.1 to 10 parts by mass of an aromatic carbodiimide compound, preferably 100 parts by mass of a resin composition mainly composed of a lactic acid resin. 1 to 5 parts by mass are added. If it is in the range of 0.1 to 10 parts by mass, the hydrolysis resistance improving effect is exhibited, and the appearance defect of the molded product due to the bleedout of the carbodiimide compound and the deterioration of the mechanical properties due to plasticization do not occur.

  At this time, it is important to select an aromatic carbodiimide compound as the carbodiimide compound. By blending the aromatic carbodiimide compound, hydrolysis resistance can be imparted by selectively reacting with a carboxyl group of a resin composition containing a lactic acid resin as a main component and reducing the acid catalyst. On the other hand, in the aliphatic carbodiimide compound, the activity is lost due to the reaction with the hydroxyl group of the metal hydroxide, and the effect of imparting hydrolysis resistance to the lactic acid resin becomes dilute when an injection molded article is formed.

Examples of the carbodiimide compound include those having a basic structure represented by the following general formula.
-(N = C = N-R-) n-
In the above formula, n represents an integer of 1 or more, and R represents an aromatic organic bond unit. Moreover, n is normally determined suitably between 1-50.

  Specific examples include bis (dipropylphenyl) carbodiimide, poly (4,4′-diphenylmethanecarbodiimide), poly (p-phenylenecarbodiimide), poly (m-phenylenecarbodiimide), poly (diisopropylphenylenecarbodiimide), poly (methyl). -Diisopropylphenylenecarbodiimide), poly (triisopropylphenylenecarbodiimide) and the like. These carbodiimide compounds can be used alone or in combination of two or more.

(Preferred formulation)
As a compounding quantity of the resin composition (A) which has lactic acid resin as a main component, the metal hydroxide (B) surface-treated with the silane coupling agent, and the aromatic carbodiimide compound (C), A) It is preferable to mix | blend 25-100 mass parts of (B) with respect to 100 mass parts, and it is more preferable to mix | blend 40-80 mass parts. Moreover, as a compounding quantity of (C), it is preferable to mix | blend 0.1-10 mass parts of (C) with respect to 100 mass parts of (A), and it is preferable to mix | blend 1-8 mass parts. By blending (A), (B) and (C) within such a range, excellent flame retardancy and durability can be imparted to a resin composition containing a lactic acid resin as a main component.

  Moreover, as a mixing ratio of the lactic acid resin (D) in the resin composition containing the lactic acid resin as a main component and the aliphatic polyester other than the lactic acid resin, and / or the aromatic aliphatic polyester (E), (D) :( E) = 50: 50 to 100: 0 is preferable, and 60:40 to 80:20 is more preferable. By blending (D) and (E) within such a range, the impact resistance of the lactic acid resin can be further improved.

(Ester compound having a molecular weight of 200 to 1000)
In order to further improve the impact resistance of the injection molded product in the present invention, it is also effective to further blend an ester compound having a molecular weight of 200 to 1000.
Examples of the ester compound having a molecular weight of 200 to 1000 used in the present invention include diisodecyl adipate, di (2-ethylhexyl) azelate, di (2-ethylhexyl) sebacate, di (2-ethylhexyl) dodecanedionate, acetyl tributyl citrate, dibutyl seba Kate, di (2-ethylhexyl) adipate, diisononyl adipate, dimethyl adipate, dibutyl adipate, tributyl citrate, acetyl tributyl citrate, triethyl citrate, diisobutyl adipate, di (2-ethylhexyl) dodecanedionate, dibutyl phthalate, diisononyl phthalate 2-ethylhexyl benzyl phthalate, dimethyl phthalate, diheptyl phthalate, diisodecyl phthalate, di (2-ethylhexyl) Tallates, tris (2-ethylhexyl) trimellitate, tributyl trimellitate, tri (2-ethylhexyl) trimellitate, glycerol triacetate, and polyethylene glycol. Of these, diisodecyl adipate, di (2-ethylhexyl) adipate, and di (2-ethylhexyl) azelate are preferable.

The molecular weight of the ester compound is important to be in the range of 200 to 1000, and more preferably in the range of 250 to 500. Below this range, it becomes difficult to obtain an effect of improving the impact resistance, and there is a possibility that the ester compound bleeds out to the surface of the molded product. On the other hand, if it exceeds this range, it will be difficult to obtain the impact resistance improving effect, and the impact resistance of the molded product will be lowered.
Moreover, as a compounding quantity of the said ester compound, it is preferable to mix | blend 0.1-5 mass parts of ester compounds with a molecular weight of 200-1000 with respect to 100 mass parts of resin compositions which have a lactic acid resin as a main component. More preferably, 0.5 to 3 parts by mass is blended. By mix | blending within the range of 0.1-5 mass parts, impact resistance can be improved, without impairing heat resistance.

(Crystallization accelerator)
In order to improve the heat resistance of the injection-molded product, it is preferable to perform crystallization treatment. However, in the case of a resin composition containing a lactic acid resin as a main component, the crystallization speed is very slow. Is preferably blended to shorten the crystallization time.

As the crystallization accelerator, talc, kaolin, calcium carbonate, bentonite, mica, sericite, glass flake, graphite, magnesium hydroxide, aluminum hydroxide, antimony trioxide, barium sulfate, zinc borate, hydrous calcium borate, Examples include alumina, magnesia, wollastonite, zonotlite, sepiolite, whiskers, glass fibers, glass flakes, metal powder, beads, silica balloons, shirasu balloons, or a mixture of two or more of these. it can.
In addition, the surface of the inorganic crystallization accelerator can be treated with titanic acid, fatty acid, silane coupling agent, etc. to improve the adhesion with the resin, and the effect of the inorganic crystallization accelerator can be improved. It is.

  The compounding amount of the crystallization accelerator is preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the resin composition containing a lactic acid resin as a main component. . If it is the range of 0.1-10 mass parts, the acceleration | stimulation effect of the crystallization speed can be provided, without impairing impact resistance.

(Other ingredients)
It is possible to formulate additives such as a heat stabilizer, an antioxidant, a UV absorber, a light stabilizer, a lubricant, a pigment, a dye, and a plasticizer as long as the effects of the present invention are not impaired.

(Production method)
Next, the molding method of the injection molded body in the present invention will be described.

First, a predetermined amount of a resin composition containing a lactic acid resin as a main component, a metal hydroxide surface-treated with a silane coupling agent, an aromatic carbodiimide compound, and other additives are the same. Each raw material is put into an injection molding machine and mixed. Specifically, the raw material is directly mixed using an injection molding machine and injection molded, or the dry blended raw material is extruded into a strand shape using a twin-screw extruder to produce pellets and then injected again. A method of creating an injection-molded body using a molding machine can be employed. In any method, it is necessary to consider a decrease in molecular weight due to decomposition of the raw material, and the latter is preferably selected for uniform mixing.
For example, a resin composition containing a lactic acid resin as a main component, a metal hydroxide surface-treated with a silane coupling agent, an aromatic carbodiimide compound, and other additives are sufficiently dried to remove moisture. After removal, the mixture may be melt-mixed using a twin screw extruder and extruded into a strand shape to produce pellets.
At this time, regarding the melt extrusion temperature, the melting point changes depending on the composition ratio of the L-lactic acid structure and the D-lactic acid structure, and the melting point of the mixed resin changes depending on the mixing ratio of the aromatic aliphatic polyester. It is preferable to set appropriately. In practice, a temperature range of 160-230 ° C. is usually selected.

  The pellets prepared by the above method may be sufficiently dried to remove moisture and then injection molded by the following method.

  That is, the injection molding method is not particularly limited, but typically, an injection molding method such as a general injection molding method, a gas assist molding method, and an injection compression molding method for thermoplastic resins may be employed. In addition to the above methods, an in-mold molding method, a gas press molding method, a two-color molding method, a sandwich molding method, PUSH-PULL, SCORIM, or the like can also be employed according to other purposes.

The injection molding apparatus is composed of a general injection molding machine, a gas assist molding machine, an injection compression molding machine, and the like, and a molding die used for these, ancillary equipment, a mold temperature control device, a raw material drying device, and the like. However, the present invention is not limited to such a configuration.
Molding conditions are preferably such that the molten resin temperature is in the range of 170 ° C. to 210 ° C. in order to avoid thermal decomposition of the resin in the injection cylinder.

  When obtaining an injection molded body in an amorphous state, it is preferable to make the mold temperature as low as possible from the viewpoint of shortening the cooling time of the molding cycle (mold closing-injection-holding pressure-cooling-mold opening-removing). . Generally, it is also desirable to use a chiller at 15 to 55 ° C. However, the range of 20 to 40 ° C. is advantageous in terms of suppressing shrinkage, warpage, and deformation of the molded body during post-crystallization.

In order to further improve the heat resistance of the molded product obtained by injection molding, it is effective to perform crystallization by heat treatment.
As a method of crystallization, a method of injection molding into a mold heated in advance and crystallizing in the mold, a method of increasing the temperature of the mold after injection molding and crystallizing in the mold, or Examples thereof include a method in which the injection molded body is taken out of the mold in an amorphous state and then heat-treated with hot air, steam, hot water, a far-infrared heater, an IH heater, or the like. At this time, it is not necessary to fix the injection molded body, but it is preferable to fix it with a mold, a resin mold or the like in order to prevent deformation of the molded body. Further, in consideration of productivity, heat treatment can be performed in a packed state.

In order to crystallize in the mold, it is preferable to hold the molten resin in the heated mold and then hold it in the mold for a certain time.
At this time, the mold temperature is preferably 80 ° C. to 130 ° C., particularly 90 ° C. to 120 ° C., and the cooling time is 1 to 300 seconds, preferably 5 to 30 seconds. By performing the crystallization treatment in the mold at such temperature and cooling time, the heat resistance of the injection-molded product in the present invention can be further improved.

When crystallizing after taking out a molded object from a metal mold | die, it is preferable to make the heat processing temperature into the range of 60-130 degreeC, and the range of 70-90 degreeC is more preferable. When the heat treatment temperature is lower than 60 ° C., crystallization does not proceed in the molding step, and when it is higher than 130 ° C., deformation or shrinkage may occur during cooling of the molded body.
The heating time is preferably determined appropriately depending on the composition and the heat treatment temperature. For example, in the case of 70 degreeC, it is preferable to heat-process for 15 minutes-5 hours. In the case of 130 ° C., heat treatment is preferably performed for 10 seconds to 30 minutes.

  The injection-molded article of the present invention is a flame-retardant injection-molded article having excellent flame retardancy and durability, and can be used as a building material, home appliance, automobile part, other general molded article, It can be suitably used for applications requiring heat resistance.

  Examples are shown below, but the present invention is not limited by these. In addition, the result shown in an Example evaluated by the following method.

(1) Flame retardance Using a test piece having a length of 135 mm, a width of 13 mm, and a thickness of 3 mm, measurement was performed based on the safety standard UL94 vertical combustion test of Underwriters laboratories.

(2) Durability A wet heat test was performed under the conditions of 85 ° C. and 80% RH, and the molecular weight retention after 100 hours was calculated by the following formula.
Molecular weight retention (%) = (mass average molecular weight after wet heat test / mass average molecular weight before wet heat test) × 100
The molecular weight retention was set at 70% or more as a practical standard. This is because the strength suddenly deteriorates from below 70%.

The mass average molecular weight was measured by the following method.
Using HLC-8120GPC manufactured by Tosoh Corporation, measurement was performed at a solvent chloroform, a solvent concentration of 0.2 wt / vol%, a solution injection amount of 200 μl, a solvent flow rate of 1.0 ml / min, and a solvent temperature of 40 ° C. The mass average molecular weight of a resin composition containing a resin as a main component was calculated. The mass average molecular weights of the standard polystyrene used at this time are 20000, 670000, 110000, 35000, 10,000, 4000,600.

(Example 1)
Nature Works 4032D (L-lactic acid / D-lactic acid = 98.6 / 1.4, weight average molecular weight 200,000) manufactured by Cargill Dow as a lactic acid resin, and Nippon Light Metal as a metal hydroxide treated with a silane coupling agent Epoxy silane coupling treatment BF013ST (aluminum hydroxide, average particle size 1 μm) manufactured by the company, and Starbaksol I (bis (diisopropylphenyl) carbodiimide: aromatic monocarbodiimide) manufactured by Rhein Chemie as the aromatic carbodiimide compound, NatureWorks 4032D, epoxy After dry blending silane coupling treatment BF013ST and stavaxol I at a mass ratio of 100: 30: 5, compounded at 180 ° C. using a 40 mmφ small-size co-directional twin screw extruder manufactured by Mitsubishi Heavy Industries, Pellet shape. The obtained pellets were injection-molded with a sheet material of L200 mm × W30 mm × t3 mm using an injection molding machine IS50E (screw diameter 25 mm) manufactured by Toshiba Machine. The main molding conditions are as follows.

1) Temperature conditions: cylinder temperature (195 ° C) mold temperature (20 ° C)
2) Injection conditions: injection pressure (115 MPa) holding pressure (55 MPa)
3) Measurement conditions: Screw rotation speed (65 rpm) Back pressure (15 MPa)

  Next, the injection-molded body was left still in a baking test apparatus (DKS-5S manufactured by Daiei Kagaku Seiki Seisakusho) and heat-treated at 70 ° C. for 2 hours. Thereafter, the plate material obtained by the injection molding was cut into a length of 135 mm, a width of 13 mm, and a thickness of 3 mm, and evaluated for flame retardancy and durability. The results are shown in Table 1.

(Example 2)
After dry blending NatureWorks 4032D, epoxy silane coupling treatment BF013ST and stavaxol I at a mass ratio of 100: 50: 5, an injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
After dry blending NatureWorks 4032D, epoxysilane coupling treatment BF013ST and stavaxol I at a mass ratio of 100: 80: 5, an injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 4
After dry blending NatureWorks 4032D, epoxy silane coupling treatment BF013ST and stavaxol I at a mass ratio of 100: 50: 1, an injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
After dry blending NatureWorks 4032D, epoxy silane coupling treatment BF013ST and stavaxol I at a mass ratio of 100: 50: 8, an injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
As an aromatic carbodiimide compound, Starbaxol P (aromatic polycarbodiimide) manufactured by Rhein Chemie was used, and after dry blending Nature W NatureWorks 4032D, epoxy silane coupling treatment BF013ST, and Stavaxol P in a mass ratio of 100: 50: 5, An injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
As an aliphatic polyester other than the lactic acid resin, Bionore 3003 (poly (butylene succinate / adipate), mass average molecular weight 200,000) manufactured by Showa Polymer Co., Ltd., NatureWorks 4032D, Bionore 3003, epoxysilane coupling treatment BF013ST, and After starbaxol I was dry blended at a mass ratio of 70: 30: 50: 5, an injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
As the aromatic aliphatic polyester, ECOFLEX F (poly (butylene adipate / terephthalate)) manufactured by BASF, and SG-95 (talc, particle size 2.4 μm) manufactured by Nippon Talc Co., Ltd. as a crystallization accelerator were used. NatureWorks 4032D, ECOFLEX F Epoxysilane coupling treatment BF013ST, stavaxol I, and SG-95 were dry blended at a mass ratio of 70: 30: 50: 5: 10, and then the same as in Example 1 using an injection molding machine. A sample subjected to crystallization treatment in a mold at a mold temperature of 110 ° C. and a cooling time of 60 seconds was prepared and evaluated. The results are shown in Table 1.
The injection conditions other than the mold temperature and the cooling time are the same as those in the first embodiment.

(Comparative Example 1)
Production and evaluation of an injection molded product of NatureWorks 4032D were performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 2)
After dry blending NatureWorks 4032D and epoxysilane coupling treatment BF013ST at a mass ratio of 100: 50, an injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 3)
Example 1 After dry blending NatureWorks 4032D, epoxysilane coupling treatment BF013ST, and carbodilite HMV-8CA at a mass ratio of 100: 50: 5 using Nisshinbo Carbodilite HMV-8CA as an aliphatic carbodiimide compound. The injection molded products were prepared and evaluated in the same manner as described above. The results are shown in Table 2.

(Comparative Example 4)
Example 1 After dry blending NatureWorks 4032D, epoxysilane coupling treatment BF013ST, and carbodilite HMV-8CA at a mass ratio of 100: 50: 10 using Nisshinbo Carbodilite HMV-8CA as an aliphatic carbodiimide compound. The injection molded products were prepared and evaluated in the same manner as described above. The results are shown in Table 2.

(Comparative Example 5)
As a metal hydroxide, BF-013S manufactured by Nippon Light Metal Co., Ltd. (stearic acid-treated aluminum hydroxide, average particle diameter of 1 μm) was used, and NatureWorks 4032D, BF-013S, and Starvacol I were used at a mass ratio of 100: 50: 5. After dry blending, an injection molded product was produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

As is clear from Table 1, the injection molded articles of Examples 1 to 8 have a flame retardancy based on UL94 satisfying V-2, and have a molecular weight after 100 hours at 85 ° C. and 80% RH. It was found that the retention rate was 70%, and both flame retardancy and durability were excellent.
On the other hand, Comparative Example 1 was inferior in both flame retardancy and durability, and Comparative Examples 2 to 4 were inferior in durability although excellent in flame retardancy. Thus, the injection molded articles of Comparative Examples 1 to 4 were impractical in either flame retardancy or durability.

Claims (5)

  A composition comprising a resin composition (A) containing a lactic acid resin as a main component, a metal hydroxide (B) surface-treated with a silane coupling agent, and an aromatic carbodiimide (C). Flame retardant injection molded body provided.   The flame retardant according to claim 1, comprising 25 to 100 parts by mass of the metal hydroxide (B) and 0.1 to 10 parts by mass of the aromatic carbodiimide (C) with respect to the resin composition (A). Injection molded body.   The flame-retardant injection-molded article according to claim 1 or 2, wherein the silane coupling agent is an epoxy silane coupling agent.   The flame-retardant injection-molded article according to any one of claims 1 to 3, wherein 0.1 to 5 parts by mass of an ester compound having a molecular weight of 200 to 1000 is blended with the resin composition (A). The resin composition (A) is blended with 0.1 to 10 parts by mass of a crystallization accelerator, and in a mold during injection molding, the mold temperature is 80 to 130 ° C. and the cooling time is 1 to 300 seconds. The flame-retardant injection-molded article according to any one of claims 1 to 4, wherein the flame-retardant injection-molded article is subjected to crystallization treatment.