JPH0212259B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to crystalline resin compositions. BACKGROUND OF THE INVENTION Crystalline resins such as crystalline polyolefin resins are widely put to practical use by injection molding, extrusion molding, blow molding, rotational molding, film molding, and the like. When molding the above-mentioned crystalline resin, purposes such as improving the transparency of the resin, suppressing sink marks, improving dimensional stability, improving gloss, improving mechanical properties, shortening the molding cycle, etc. It is known to add a nucleating agent to the resin. Nucleating agents added for this purpose include, for example, 1,3:2,4-dibenzylidene sorbitol (DBS), 1,3:
2,4-dibenzylidene xylitol (DBX)
There are known unsubstituted compounds such as , and symmetrically substituted compounds such as symmetrically substituted DBS and symmetrically substituted DBX in which the same substituents are substituted on each of the two aromatic rings in these compounds. However, such known nucleating agents have the following drawbacks. For example, non-substituted nucleating agents have sublimation properties and are therefore unsuitable for extrusion molding, and it is also difficult to shorten the molding cycle in other molding methods. In addition, it is inevitable that a precipitate phenomenon occurs in resin molded products obtained by blending non-substituted nucleating agents, and further improvement in the transparency of the resin molded products is desired. Furthermore, among the symmetrically substituted nucleating agents, lower alkoxy-substituted nucleating agents have poor compatibility with resins, and therefore, a bleed-out phenomenon inevitably occurs in resin molded articles obtained by blending the nucleating agents. Among the symmetrically substituted nucleating agents, lower alkyl substituted nucleating agents no longer have a nucleating effect when substituted with butyl, and the effect of the nucleating agent with propyl substitution is small relative to the ratio of the amount added. Methyl, ethyl, and chlorine substituted products are far superior to unsubstituted products in terms of sublimability and effectiveness. However, all three have high melting points of 240°C or higher, and their solubility in resins is poor, so the molding temperature must be raised as necessary. Among symmetrically substituted nucleating agents, halogen-substituted nucleating agents, for example, chloro-substituted products, have a melting point of 245°C, and under normal processing conditions of 220°C or lower, fissures occur throughout the molded product, making it impossible to put them to practical use. For this reason, it is completely unsuitable for polyethylene resin, and in the case of polypropylene resin, a special high-temperature masterbatch is required, but it has insufficient thermal stability and has a strong tendency to decompose, resulting in sideways deformation of the molded product. Furthermore, among symmetrically substituted nucleating agents, nitro-substituted nucleating agents also have the same drawbacks as above. Furthermore, as a nucleating agent, O-benzylidene-O-p-
A technique using chlorobenzylidene sorbitol is also known (Japanese Unexamined Patent Publication No. 161444/1983). However, when O-benzylidene-O-p-chlorobenzyldensorbitol is used as a nucleating agent, it is recognized that it is particularly superior to the above-mentioned unsubstituted nucleating agent and symmetrically substituted nucleating agent. I can't. In addition, the halogen substituent is likely to be eliminated during high-temperature molding, and the resulting hydrochloric acid has insufficient thermal stability and performance cannot be maintained. Furthermore, film molding of low density polyethylene and linear low density polyethylene has a too high melting point, making it impractical. A fatal drawback arises in that it is impossible to obtain a uniform film thickness when the molding temperature is 200°C or higher. In addition, even when any of the above-mentioned known nucleating agents is used, the crystallization temperature of the resulting resin composition is relatively low, and therefore, in order to improve workability during molding, it is desirable to further improve the crystallization temperature. Furthermore, it is desired to further improve the mechanical properties such as tensile strength of the resulting resin molded products. In view of the current situation, the present inventors have conducted intensive research to develop a nucleating agent that meets the above requirements, and have discovered that a compound represented by the following general formula () can be a desired nucleating agent. The present invention was finally completed. That is, the present invention provides crystalline resin with the general formula [In the formula, R ¹ and R ² each represent a hydrogen atom, a lower alkyl group, a lower alkoxyl group, or a nitro group. m and n each represent 0 or an integer of 1 to 5. p represents 0 or 1. However, if p is 0 and R ¹ and R ² represent the same group, m≠
It is assumed that n. Further, when p is 1, at least one of m and n represents an integer of 2 to 5, and m≠n. The present invention relates to a crystalline resin composition characterized in that it contains a compound represented by the following. The compound represented by the above general formula [] does not have any of the drawbacks of conventionally known nucleating agents. That is, the compound represented by the general formula [] does not have sublimation properties, and therefore, a resin composition containing the compound can be molded by various molding methods such as injection molding, extrusion molding, blow molding, rotation molding, and film molding. It can be molded by Also general formula []
The compound represented by the formula has excellent compatibility with resins, and therefore, a bleed-out phenomenon does not occur in a resin molded article obtained by blending the compound. Furthermore, the crystallization temperature of the resin composition containing the compound represented by the general formula [] is relatively high, the workability during molding is good, and the resulting resin molded product has mechanical properties such as transparency and tensile strength. Properties etc. can also be further improved. In addition, improved transparency and dimensional safety can also be effectively obtained in film molding. These effects are simply properties that cannot be obtained with blends of known nucleating agents, such as 1:1 blends of DBS and p-methyl-substituted DBS. Further, in the present invention, there are no problems caused by halogen atoms as in the prior art. In the compound represented by the above general formula [] used in the present invention, examples of lower alkyl groups defined by R ¹ and R ² include methyl, ethyl, propyl, butyl groups, and examples of lower alkoxy groups include methoxy and ethoxy groups. , propoxy, butoxy groups and the like. Specific examples of the compound represented by the general formula [] used in the present invention are as follows. O-p-isopropylbenzylidene-O-2,
4-dimethylbenzylidene sorbitol O-p-isopropylbenzylidene-O-2,
4,5-trimethylbenzylidene sorbitol O-benzylidene-O-2,4-dimethylbenzylidene sorbitol O-p-ethylbenzylidene-O-2,4-dimethylbenzylidene sorbitol O-p-methoxybenzylidene-O-2,4,
5-Trimethylbenzylidene sorbitol O-p-ethoxybenzylidene-O-2,4-
Dimethylbenzylidene sorbitol Similarly, there is a xylitol form. O-p-isopropylbenzylidene-O-p-
Methoxybenzylidene xylitol O-p-isopropylbenzylidene-O-p-
Methylbenzylidenexylitol O-p-isopropylbenzylidene-O-benzylidenexylitol O-p-isopropylbenzylidene-O-2,
4-dimethylbenzylidenexylitol O-p-isopropylbenzylidene-O-2,
4,5-trimethylbenzylidenexylitol O-p-isopropylbenzylidene-O-p-
Nitrobenzylidenexylitol O-p-Isopropylbenzylidene-O-p-
Butoxybenzylidene xylitol O-p-isopropylbenzylidene-O-tert
-Butylbenzylidenexylitol O-benzylidene-O-p-methyl-benzylidenexylitol O-benzylidene-O-2,4-dimethylbenzylidenexylitol O-benzylidene-O-p-methoxybenzylidenexylitol O-benzylidene-O-p-ethoxybenzylidene Xylitol O-benzylidene-O-p-ethylbenzylidenexylitol O-p-isopropylbenzylidene-O-p-
Ethylbenzylidenexylitol O-p-methylbenzylidene-O-p-ethylbenzylidenexylitol O-p-methylbenzylidene-O-p-methoxybenzylidenexylitol O-p-methylbenzylidene-O-p-tret-
Butylbenzylidenexylitol O-p-ethylbenzylidene-O-p-methoxybenzylidenexylitol O-p-ethylbenzylidene-O-p-nitrobenzylidenexylitol O-p-ethylbenzylidene-O-2,4-dimethylbenzylidenexylitol O-p -methoxybenzylidene-O-2,4,
5-Triethylbenzylidenexylitol O-p-ethoxybenzylidene-O-2,4-
Dimethylbenzylidenexylitol Op-ethoxybenzylidene-Om-nitrobenzylidenexylitol The compound represented by the general formula [] is produced, for example, by the following method. In the presence of a mineral acid such as nitric acid, benzaldehyde and sorbitol, preferably an aqueous sorbitol solution, are mixed at room temperature in an equimolar ratio. The precipitated product is neutralized, separated, dried and then recrystallized from water. The crystals obtained are 2,4
-benzylidene sorbitol. This is separated into a suitable solvent such as benzene, toluene, xylene, cyclohexane, etc., preferably in equimolar proportions with the aldehyde, and a mineral acid such as nitric acid is added thereto, heated if necessary, and the produced water is removed. In this way, the desired product can be obtained in a high yield, for example about 85%. In addition, the following method can be exemplified as another method. That is, a mixture of two or more different aldehydes and approximately half of the sorbitol are dispersed in an organic solvent such as cyclohexane,
By distilling the produced water out of the system in the presence of a mineral acid, neutralizing the product, washing with water, and drying, the desired product can be easily obtained as a mixture. In each of the above methods, if xylitol is used instead of sorbitol, the target xylitol compound can be obtained in the same manner. As the crystalline resin, a wide range of conventionally known ones can be used, such as ethylene homopolymer (high purity, medium density, low density polyethylene), ethylene content 50%
Crystallinity of ethylene copolymers, propylene homopolymers, propylene copolymers with a propylene content of 50% or more, butene homopolymers, butene copolymers with a butene content of 50% or more, metal pentene homopolymers, methylpentene copolymers with a methylpentene content of 50% or more, etc. Examples include olefin resins and polybutadiene. The copolymer may be a random copolymer,
It may also be a block copolymer. In addition, comonomers that can constitute the above copolymer include ethylene, propylene, butene, pentene, hexene,
Any of various _C7 to _C18 olefins can be used, specifically α-olefins such as vinyl acetate, ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, dodecene, etc. , methyl acrylate,
Examples include acrylic esters such as ethyl acrylate, methacrylic esters such as methyl methacrylate, and ethyl methacrylate. In the present invention, it is also possible to use a resin in which a polymer such as polyisobutylene, polybutene, terpene phenol resin, etc. is suitably blended with the above resin. The amount of the compound represented by the general formula [] in the above resin is not particularly limited and can be appropriately selected from a wide range, but is usually 0.01~
The amount is preferably 30% by weight, preferably 0.05-10% by weight. By blending within these ranges, the desired effects of the present invention can be sufficiently exhibited. The composition of the present invention may contain antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, crosslinking agents, crosslinking accelerators, foaming agents, colorants, dispersants, fillers, and antistatic agents depending on the purpose and use. Various components such as the following can be appropriately blended. When producing the composition of the present invention, any conventionally known method can be applied. For example, the compound of the general formula [] may be directly blended with the crystalline resin,
The above compound may be blended with the resin in advance and pelletized. Further, when molding the composition of the present invention, any conventionally known molding method can be employed. Examples and comparative examples are listed below. In each example, the middle part means part by weight. Example 1 80 parts by weight of LLDPE resin (MI0.5), 20 parts by weight of LDPE resin (MI0.8), and 0.2 parts by weight of the nucleating agent shown in Table 1 below.
After tri-blending the weight part, it is thickened at 180℃.
A 40 μm inkling film was produced.
The transparency of the obtained film was measured. The results are shown in Table 1 below.

【table】

[Table] Example 2 65 parts by weight of polyprene homopolymer (MI1.0),
25 parts by weight of random polypropylene containing 7% ethylene (MI1.0), 5 parts by weight of block polypropylene containing 20% ethylene, 5 parts by weight of the above random polypropylene containing 5% of the specified asymmetric dibenzylidene sorbitol shown in Table 2 below, and calcium stearate. 0.2 parts by weight were melt-mixed and extruded at 230° C. for 5 minutes using a twin-screw laboplasto mill, and a sheet with a thickness of 0.5 mm was produced by an air cooling method. The physical properties of the sheet thus obtained are shown in Table 2 below.
However, for comparison, Table 2 below also shows the results obtained when no nucleating agent was used and when the same treatment was performed using a known nucleating agent.

【table】

[Table] Molding speed can be increased.
Note 2) Tensile strength (Kg/cm ² )
Example 3 To 100 parts by weight of ethylene-containing 4% random polypropylene (M19), a specified amount of the specified nucleating agent listed in Table 3 below was added, and the mixture was heated at 220 parts by weight using a two-screw laboratory plastomill.
Mixed for 5 minutes at °C. Subsequently, it was pressed at 100 kg/cm ² at 200° C. for 3 minutes and cooled with water to obtain a sheet with a thickness of 1 mm.

[Table] Example 4 Polybutadiene RB820 [Japan Synthetic Rubber Co., Ltd.] 100
Parts by weight, 0.3 parts by weight of the specified nucleating agent below were melt-mixed at 125℃ for 5 minutes in a two-screw laboplasto mill, and 40Kg/
Press molding was carried out for 3 minutes at 120° C. cm ² . The results of measuring the physical properties of the obtained sheet are shown in Table 4 below. For comparison, cases in which no nucleating agent was used and cases in which a conventional nucleating agent was used are also shown.

[Table] Note that ΔTc is the value obtained by subtracting the Tc of No. 1 without a nucleating agent from the actual Tc. The larger ΔTc is, the higher the temperature is for crystallization, and the molding speed can be further increased.

Claims (1)

[Claims] 1. The crystalline resin has the general formula [In the formula, R ¹ and R ² each represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, or a nitro group. m and n each represent 0 or an integer of 1 to 5. p represents 0 or 1. However, if p is 0 and R ¹ and R ² represent the same group, m≠
It is assumed that n. Further, when p is 1, at least one of m and n represents an integer of 2 to 5, and m≠n. ] A crystalline resin composition characterized by blending a compound represented by the following.