JPS5936644B2 - Polyoxymethylene resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to reinforced polyoxymethylene resin compositions.

More specifically, the present invention relates to a reinforced polyoxymethylene resin composition in which the reinforcing effect is improved by forming a strong bond between a non-carbon-based inorganic filler and polyoxymethylene. Compositions in which polyoxymethylene is blended with an inorganic filler have been known so far.

However, unlike other thermoplastics such as polyamides and polyesters, polyoxymethylene
Since there is no active contact between the blended inorganic filler particles and the base resin, there is a drawback that a sufficient reinforcing effect cannot be exhibited. For this reason, several attempts have been made to improve the reinforcing effect by activating the contact between polyoxymethylene and an inorganic filler in combination.

For example, a method for producing glass fiber-reinforced polyoxymethylene by copolymerizing trioxane and a comonomer in the presence of glass fibers impregnated with silane or siloxane containing epoxide groups (Japanese Patent Publication No. 47-4214
Japanese Patent Publication No. 49-1463 and Japanese Patent Publication No. 49-2974 have been proposed. However, although these methods may be somewhat effective in improving local physical properties, they are hardly able to achieve large-scale improvements in overall properties. Furthermore, by blending glass fiber or glass fiber that has been previously treated with a urethane compound or an aminoalkylsilane condensation product into the mixture of polyoxymethylene and an isocyanate compound, the polyoxymethylene and glass fiber can be mixed through an intermediate layer. Method for improving mechanical properties by bonding
No. 259, JP-A-46-6388, JP-A-4
7-13435) is also known. These methods are promising in practice as they show fairly substantial effects, but even if they are effective for polyoxymethylene copolymers, they are not effective for polyoxymethylene homopolymers. The disadvantage is that the scope of application is inevitably limited because of the inability to do so. For example, Jiyuracon M9O-0
2 (registered trademark name of polyoxymethylene copolymer manufactured by Polyplastics Co., Ltd.) was confirmed to be effective, but it was found to be effective against Tenac 5010 (registered trademark name of polyoxymethylene homopolymer manufactured by Asahi Kasei Corporation). No effect was observed on In view of these facts, the present inventors have made polyoxymethylene and an inorganic filler substantially bonded at their interface to enhance the reinforcing effect, hardly discolor due to heat, and moreover, We conducted intensive research to develop a new polyoxymethylene-reinforced composition that could also be applied to coalescence, and first developed a mixture of polyoxymethylene and carbon fiber, a specific polymerizable binder, and a radical. Although they succeeded in obtaining a carbon fiber-reinforced composition by blending a polymerization initiator in a specific ratio and melt-kneading it, further research revealed that this technology could also be applied to inorganic fillers other than carbon fiber. Based on this knowledge, the present invention was completed.

That is, the present invention provides (a) polyoxymethylene 100
(b) 5 to 150 parts by weight of a non-carbon inorganic filler, (c) 0.01 to 5 parts by weight of a radical polymerization initiator, and (d) 0.1 to 20 parts by weight of acrylamide or N-methylolacrylamide. A reinforced polyoxymethylene resin composition comprising a heated kneaded product is provided.

The reinforced polyoxymethylene composition according to the present invention exhibits remarkable improvements in tensile strength, elongation, impact strength, as well as strength and elastic modulus at high temperatures, as compared to a composition simply mixed with a filler.

In comparison with prior art, the present invention employs glass fiber fillers as compared to the aforementioned styrenic resin-coated or polymerized compositions on silane-impregnated glass fibers.
Much higher overall mechanical properties.

Furthermore, compared to the glass fiber reinforced polyoxymethylene copolymer compositions produced by the aforementioned patents that use isocyanate compounds, the glass fiber reinforced material according to the present invention has almost the same mechanical properties. Furthermore, the molded product has an excellent white color tone and is characterized by extremely little discoloration due to heat. More importantly, while the above-mentioned known methods cannot necessarily effectively reinforce polyoxymethylene homopolymers, the present invention can be applied to both homopolymers and copolymers. This has the significant advantage of being able to provide highly reinforced compositions. The polyoxymethylene used in the present invention may be a homopolymer as described above, that is, a polymer obtained by polymerizing formaldehyde or trioxane (including one whose terminals have been stabilized), or a polymer obtained by polymerizing formaldehyde or trioxane. It may also be a binary, ternary or more copolymer obtained by copolymerizing the monomer and a comonomer such as a cyclic ether or a cyclic acetal.

In particular, terminally stabilized homopolymers are most preferred. According to the present invention, any type of non-carbon-based inorganic filler can have the effect of improving reinforcing properties. The shape may be powder, flake, needle, fiber, or the like. Considering the stability of polyoxymethylene during mixing, fillers with a pH in the range of 6 to 10 are preferred, and fillers with a pH in the range of 6.5 to 9 are more preferred. Examples of non-carbon inorganic fillers that can be used include glass fibers, glass beads, silica, calcium silicate, mica, clay, talc, asbestos, calcium carbonate, slag, magnesium carbonate, alumina, and various other metal salts and oxides. , hydroxide or mixtures thereof. Particularly preferred examples include glass fibers, glass beads, calcium silicate, talc, and calcium carbonate. The surface of these fillers does not need to be specially treated, but
Surface treatments such as those commonly used for plastics formulations may also be used.

The amount of the non-carbon inorganic filler is selected in the range of 5 parts by weight to 150 parts by weight based on 100 parts by weight of polyoxymethylene.

If the amount is less than 5 parts by weight, the range of properties imparted by the filler is extremely small, so the effects of the present invention cannot be fully exhibited, and if it exceeds 150 parts by weight, Since it is difficult to uniformly disperse each component, an effective reinforcing effect cannot be obtained.

In addition, 10 to 1 per 100 parts by weight of polyoxymethylene
00 parts by weight can be cited as a more preferred range of the amount of non-carbonaceous inorganic filler. The radical polymerization initiator is an essential component that characterizes the present invention, along with acrylamide or N-methylolacrylamide, which will be described below.

Even if any of these is missing, the effect of the present invention will not be exhibited at all. The radical polymerization initiator used in the present invention is, for example, an organic peroxide, such as tertiary-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide. , 2,5-dimethylhexane-2,5-dihydroperoxide, ditert-butyl peroxide, digmyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and the like. be.

Mixtures of two or more of these may also be used. Other than organic peroxides, azobisnitriles such as azobisisobutyronitrile can also be used. The amount of the radical polymerization initiator used is related to the reinforcing effect of the composition, and there is a range that provides the optimum effect.

This varies to some extent depending on the type of initiator, the molecular weight of polyoxymethylene, the amount of acrylamide or N-methylolacrylamide used, etc., but the generally preferred range is 0 to 100 parts by weight of polyoxymethylene.
．． 01 to 5 parts by weight. A more preferable range is 0.05 to 1 part by weight. The use of acrylamide or N-methylolacrylamide is the most distinctive feature of the present invention. It is truly surprising that these two types of vinyl monomers are the only ones that can form a substantial bond between polyoxymethylene and the inorganic filler. Not only vinyl monomers, but even compounds chemically similar to these, such as methacrylamide, N·N-dimethylacrylamide, and N-N-methylenebisacrylamide, have no reinforcing effect at all. It is not shown. There is also an optimum range for the amount of acrylamide or N-methylolacrylamide to be used; if it is too small, there will be insufficient bonding points and a sufficient reinforcing effect cannot be obtained, and if it is too large, the entire homopolymer phase such as acrylamide will be damaged. If the ratio of the amount to
Both are inappropriate.

Therefore, a suitable range is 0.1 to 20 parts by weight per 100 parts by weight of polyoxymethylene. More preferably, it is used in a range of 0.5 to 10 parts by weight. When using acrylamide or N-methylolacrylamide, mixtures thereof may be used,
Further, other radically polymerizable unsaturated monomers different from these can also be added.

Additionally, a silane-based coupling agent may be added to the non-carbon-based inorganic filler, as is commonly done.

However, in the case of the present invention, it is not necessary to use a silane coupling agent, and the reinforcing effect will be the same whether or not it is used. Further, even if only a silane coupling agent is added to a material that lacks the constituent requirements of the present invention, no effect will be brought about. In addition, the composition of the present invention contains various additives normally added to polyoxymethylene resins, such as heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, plasticizers, crystal nucleating agents, and lubricants. , pigments, etc. may be added.

In order to obtain the composition of the present invention, it is preferable to mix the constituent components using equipment usually used for kneading resin melts, such as a kneader, a roll mill, or an extruder.

An extruder is most preferable from the viewpoint of blocking oxygen and working environment. The mixing temperature is above the melting point of the polyoxymethylene used.

This is determined by the need to uniformly mix polyoxymethylene in its molten state. The upper limit of the temperature is generally limited by the stability of the polyoxymethylene used against thermal decomposition, and the mixing is usually carried out at a temperature below 250°C, preferably below 230°C. The mixing order requires that all components be kneaded substantially simultaneously.

Specifically, "substantially simultaneously" means that the polymerization reaction of acrylamide or N-methylol acrylamide and the reaction of polyoxymethylene with a radical polymerization initiator are carried out simultaneously, and at that time, polyoxymethylene, This means that the components of the radical polymerization initiator, acrylamide or N-methylolacrylamide, and the carbon-based inorganic filler are being uniformly dispersed or have already been dispersed. The most suitable mixing method is to simultaneously feed all the components into the above-mentioned apparatus and knead them while the polyoxymethylene is in a molten state. At this time, it is preferable to pre-mix each constituent component in advance using a tumbler or pen shell mixer at a temperature that does not cause polymerization reaction to create a homogeneous composition. Although it is more preferable to use methylene in powder form for stable supply to the extruder, this is not an essential condition.
Other examples of substantially simultaneous mixing include a method in which polyoxymethylene is kneaded with a non-carbon inorganic filler in advance, and this is mixed with the remaining components and reacted with the non-carbon inorganic filler. It is also possible to apply a method in which unpolymerized acrylamide or N-methylolacrylamide is attached to the surface in advance, and this is kneaded into polyoxymethylene together with a radical polymerization initiator. The time required for kneading will vary depending on the specific method of implementation, but may be comparable to the time required to mix only the filler into the polyoxymethylene, especially if additional kneading time is required beyond that. There is no need to add .

The composition melt-kneaded as described above may be subjected to extrusion molding or calendar molding as it is, or may be subjected to molding processes such as injection molding, compression molding, and extrusion molding after cooling.

The present invention will be explained in more detail below with reference to Examples.

Example 1 Polyoxymethylene homopolymer (Tenatsuku 5010 = Asahi Kasei Corporation registered trademark) powder. 100 parts by weight, chopped glass fiber strand (vinyl acetate treatment, 6n
), 30.15 parts by weight of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne, and 2.5 parts by weight of acrylamide were tap-linked and mixed roughly. The mixture was kneaded into pellets using an extruder set at ℃.

Regarding molded products made by injection molding, ASTMD17O8
and D256, room temperature tensile strength/elongation, 120
C. tensile strength and normal temperature Izot impact strength (notched) were measured. The results are shown in Table 1 (Table 8).Compared with the comparative example of No. 1 Kyoto q (Tj), a clear strengthening effect is recognized. Although the values are the same, it can be seen that it is superior in that there is almost no discoloration after being left at 150°C for 5 days. Comparative Example 1 The same type and amount of polyoxymethylene' and glass fiber as in Example 1 were used. Mixing, molding, and measurements were performed in the same manner as in Example 1 without adding any other additives.

The results are shown in Table 1 (old). Comparative Example 2 25 parts by weight of the same glass fiber as in Example 1 was prepared in advance.
It was coated with 5 parts by weight of a modified isocyanate (Coronate L = registered trademark of Nippon Polyurethane Industries Co., Ltd.), and this, 100 parts by weight of the same polyoxymethylene homopolymer as in Example 1, and a urethane-modified polyester for curing (
1.25 parts by weight of Nipporan 3002 (registered trademark of Nippon Polyurethane Industries, Ltd.) was mixed in the same manner as in Example 1, molded, and measured.

The results are shown in the first yellow q, and no reinforcing effect was observed. On the other hand, as can be seen in Comparative Example 4 (results are shown in Table 1), which will be described later, when a polyoxymethylene copolymer is used, a reinforcing effect is observed with the same formulation. It is recognized that the technology of Japanese Patent Publication No. 46-25259 or related patent publications mentioned in the text is reproduced without error. Comparative Example 3 Polyoxymethylene was copolymer (Dyuracon M9O
−92 = Polyplastics Co., Ltd. registered trademark) 1
This and the same glass fiber 25 as in Example 1 were used.
parts by weight were mixed and molded in the same manner as in Example 1 without adding any other additives, and the measurements were performed.

The results will be shown to the first Sadaguchi. Comparative Example 4 Comparative Example 2 except that the same copolymer as Comparative Example 3 was used as polyoxymethylene.
The first yellow line shows the results of molding and measuring a composition mixed using the same recipe and method.

Comparative Example 5 A commercially available glass fiber reinforced polyoxymethylene copolymer (Dyuracon GC-25 = Polyplastics Co., Ltd. registered trademark) was used, and in order to match the glass fiber concentration with each of the above examples, one quarter of the glass fiber concentration was used. A weight of polyoxymethylene copolymer (same as in Comparative Example 3) was added and kneaded.

This was molded in the same manner as in Example 1, and the measurement results are shown in Table 1 (G). Example 2 Mixing, molding, and measurement were carried out in exactly the same manner as in Example 1, except that a copolymer (same as in Comparative Example 3) was used as the polyoxymethylene.

The results are shown in Table 1. Even in the case of copolymers, the reinforcing effect is fully exhibited. Example 3 The glass fibers in Example 1 were treated with concentrated sulfuric acid to remove the surface treatment agent, and the other ingredients were the same as in Example 1, mixed and molded in the same manner, and the tensile strength and izot impact strength were determined. (notched) was measured.

The results are shown in Table 2 1. The strengthening effect is shown in Example 1 (Table 2 (
It is accepted to the same extent as (reprinted in A)).

Example 4 The components of Example 1 plus 0.75 parts by weight of γ-methacryloxypropyltrimethoxysilane were mixed and molded in the same manner as in Example 1, and measured in the same manner as in Example 3. Summer.

The results are shown in Table 2 (0). The reinforcing effect was observed to be almost the same as in Example 5. Example 5 In Example 1, when the same weight of N-methylol acrylamide was used instead of acrylamide, the same mixing and The results of molding and measurement are shown in Table 2 n.

A reinforcing effect is observed. Comparative Example 6 Mixing, molding, and measurement were carried out in the same manner as in the above-mentioned Examples except that acrylamide and peroxide were excluded from the components of Example 4.

The results are shown in Table 2 (G). No strengthening effect was observed compared to Comparative Example 1 (reprinted in Table 2 (5)). Comparative Example 7 Among the components of Example 4, only peroxide was excluded,
Mixing, molding, and measurement were performed in the same manner as in each of the above examples.

The results are shown in Table 2 (G). No reinforcing effect was observed.
Comparative Example 8 Among the components of Example 4, only acrylamide was excluded, and mixing, molding, and measurement were performed in the same manner as in each of the above Examples.

The results are shown in Table 2 (G). No reinforcing effect was observed.
Comparative Example 9 Among the components of Example 4, the same weight of methacrylamide was used instead of acrylamide, but mixing, molding, and measurement were carried out in the same manner as in each of the above Examples.

Claims (1)

[Claims] 1 (a) 100 parts by weight of polyoxymethylene, (b) 5 to 150 parts by weight of non-carbon inorganic filler, (c) 0.01 to 5 parts by weight of radical polymerization initiator, and (d) acrylamide or N-methylolacrylamide. 0.1~20
A reinforced polyoxymethylene resin composition comprising part by weight of a heated kneaded product.