JPS6361339B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel polypropylene compositions. More specifically, it is a novel polypropylene composition that contains a weather resistance imparting agent mainly composed of inexpensive zinc oxide (ZnO) and has further improved weather resistance than those containing conventionally known expensive weather resistance imparting agents. Regarding. Polypropylene (PP), along with vinyl chloride resin (PVC), polystyrene (PS), polyethylene (PE), etc., is manufactured, processed and sold into various products as a general-purpose resin, but the softening temperature due to heat is It is the most expensive among these general-purpose resins and is therefore widely used as a heat-resistant product. External walls, decking materials, etc. as building materials used in outdoor environments.
An example of this is insect screen for windows. however,
Although these products are required to be weather resistant because they are used outdoors, PP inherently has poor weather resistance. Competitive product PVC
The current situation is that demand for these products is sluggish due to pressure from products. Therefore, as a countermeasure, various stabilizers and
Various studies have been conducted to improve weather resistance by adding ultraviolet absorbers and the like. UV absorbers used for this purpose include salicylic acid derivatives such as phenyl salicylate and p-octylphenyl salicylate, 2,4-hydroxybenzophenone, and 2,2'-dihydroxy-4
-methoxybenzophenone, 2-hydroxy-4
-benzophenone compounds such as methoxy-5-sulfone benzophenone trihydrate, 4-dodecyloxy-2-hydroxybenzophenone, 2
-(2'-hydroxy-5'-methylphenyl)-5-
Examples include benzotriazole compounds such as chlorobenzotriazole and 2-(2'-hydroxy-4'-n-octoxyphenyl)benzotriazole. However, since these are all extremely expensive organic compounds, resin products to which these ultraviolet absorbers are added naturally end up being expensive. PP has the best heat resistance of all general-purpose resins, but its weather resistance is poor, so when trying to make outdoor products using PP, you must add a large amount of the expensive ultraviolet absorber mentioned above. It is not possible to maintain weather resistance equivalent to that of general-purpose resins. Therefore, when trying to obtain a resin product using PP that has weather resistance comparable to that of other general-purpose resins, the product cost increases, which is extremely disadvantageous. Therefore, the use of weather resistance imparting agents that are as inexpensive as possible has been considered, and the addition of rutile-type titanium white (R-TiO ₂ ), which is an inorganic compound that is relatively inexpensive compared to the organic ultraviolet absorbers mentioned above, has been proposed. has been done. However, rutile type titanium white also
It cannot be said that it is a cheap additive. For this reason, there is currently a long-awaited development of a weather resistance imparting agent that is less expensive and more effective. Usually commercially available pelleted polypropylene has poor weather resistance, so a small amount of antioxidants [such as 2,6-di-t-butyl-p-cresol and 2,6-di-t-butyl-p-cresol] are added during the granulation process. 2'-methylenebis(4-methyl-6-
Efforts have been made to impart weather resistance by adding t-butylphenol, etc., but it goes without saying that this alone is not sufficient to obtain outdoor products that require a high degree of weather resistance. Therefore, when trying to obtain a product that requires weather resistance from PP, the reality is that a considerable amount of the aforementioned R-TiO ₂ and a rather expensive organic ultraviolet absorber are added. Therefore, it goes without saying that the manufacturing cost of highly weather resistant products made from PP is higher than similar resin products made from other resins. In recent years, a mixture of zinc oxide and zinc dithiocarbamate obtained by a melting method has been announced as a new type of weather-resistant compounding agent for resins, but it has not yet achieved sufficient effects. In view of the above-mentioned circumstances, the present inventor conducted research to develop an inexpensive and effective weathering agent for polypropylene, and as a result, achieved the present invention. That is, the present invention provides zinc oxide and di-2-
It is characterized in that a mixture with zinc ethylhexyl dithiophosphate is used as a weather resistance imparting agent for polypropylene, which is particularly poor in weather resistance among general-purpose plastics. The weather resistance imparting agent of the present invention is mainly composed of zinc oxide, to which a small amount of zinc di-2-ethylhexyl dithiophosphate is added. It is particularly preferable to use zinc oxide produced by a wet method. preferable. This weather resistance imparting agent of the present invention is
The surprising fact has been confirmed that it is not only cheaper than R-TiO ₂ and the organic ultraviolet absorbers mentioned above, but also provides superior weather resistance. The weatherability imparting agent used in the present invention is mainly composed of zinc oxide, to which a small amount of zinc di-2-ethylhexyldithiophosphate is added, and the blending ratio of the two can vary within a fairly wide range. However, preferably, the proportions are such that 2.0 to 10.0 parts by weight of zinc oxide and 0.1 to 2.5 parts by weight of zinc di-2-ethylhexyl dithiophosphate are blended with respect to 100 parts by weight of polypropylene. It is preferable that zinc oxide and zinc di-2-ethylhexyldithiophosphate are mixed in advance and added to polypropylene, but they can be added separately to polypropylene so that the final mixing ratio is as described above. Good too. It is preferable to use zinc oxide obtained by a wet method, but zinc oxide obtained by a melt method can also be used. The weather resistance imparting agent used in the present invention is mainly composed of zinc oxide, but even if zinc oxide was added alone to polypropylene, the weather resistance of polypropylene could not be substantially improved. Also,
Although the combination of zinc oxide and zinc diethyldithiocarbamate is also effective as a weathering agent, it has been confirmed that its effectiveness is substantially inferior to that of the weathering agent of the present invention. The zinc oxide used as an additive in the present invention may be produced by either a melt method (generally the French method) or a wet method (for example, the method disclosed in JP-A-53-116296). However, the effect obtained by the wet method was greater. The preferred blending amount of zinc oxide (ZnO) was determined to be 2.0 to 10.0 parts by weight per 100 parts by weight of polypropylene (PP) because a blending of less than 2.0 parts by weight would not provide a sufficient effect of improving weather resistance. This is because even if 10.0 parts by weight or more is added, no substantial effect will be added. However, the above range is set practically from the viewpoint of effectiveness, and anything outside the above range is not outside the technical scope of the present invention. In addition, the amount of zinc di-2-ethylhexyldithiophosphate (Zn-D-2EHDPA)
The reason is that the content is 0.1 to 2.5 parts by weight per 100 parts by weight of PP.
If the amount is less than 0.1 part by weight, no additive effect due to the coexistence with ZnO can be obtained;
This is because even if the amount exceeds parts by weight, the effect does not increase significantly. In addition to weathering agents, polypropylene products naturally contain softeners, stabilizers,
Various additives such as lubricants are blended. Since the weather resistance imparting agent of the present invention is compatible with these various additives, no special problems arise when added together with these additives. The polypropylene composition referred to in this specification is not only a molded composition in which the above-mentioned weather resistance imparting agent is blended with a PP compound containing the various additives mentioned above other than the weather resistance imparting agent, but also a composition of a molded product which is prepared by heating, It includes all types of molded and processed PP products.
This will be explained below using examples. Example 1 The ZnO used in this experiment was produced by the above melting method.
There are two types: ZnO and ZnO produced by a wet method, which is mainly used for special purposes. This experiment was conducted using the method of the present invention (ZnO+Zn-D-
2EHDTPA) and a case in which R-TiO ₂ or an organic ultraviolet absorber was blended, and the effects were compared. First, ZnO (produced by wet method) and
A mixture (powder) with Zn-D-2-EHDTPA was prepared under the formulation conditions shown in Table 1.

[Table] According to Table 1, 500g of ZnO was added to a Henschel mixer for testing (capacity 1), and the mixture was heated at 500 r.p. at room temperature.
After stirring for m×1 minute, Zn-D-2-
Add 25g or 50g of EHDTPA in several portions over 2 minutes, then increase the rotation speed to 1500rpm.
Mix and stir for a minute. The material temperature at that time was approximately 50°C in all cases. In this case, powdered ZnO and
All of the materials obtained by blending and stirring Zn-D-2-EHDTPA (liquid) were in the form of dry powder. this
Mixtures No. 2 and No. 3 were blended as shown in Table 2.

[Table] According to the mixing ratio in Table 2, each sample was mixed with a Henschel mixer with a capacity of 3 at 2600 rpm for 1 minute.
Stir for 30 seconds. The material temperature at that time was 40°C (after the stirring was completed). A sample compounded according to Table 2 above was molded into a JIS-2 dumbbell shape (thickness 1.0 m/m) using a 4-ounce injection molding machine under the following conditions to obtain a performance test piece. Injection conditions ●Mold temperature: 50℃ ●Molding temperature: 230℃ ●Injection pressure: 50Kg/cm ² ●Specimen shape: JIS-2 dumbbell (thickness 1.0m/
m) An irradiation test was conducted on specimens corresponding to Samples No. 1 to No. 4 prepared by the above method using a sunshine carbon arc lamp specified in JIS-K-6732-(1981). Its performance and operating conditions are shown in Table 3.

[Table] Next, regarding the physical property test, the conditions are as follows. ●Tensile testing machine: Instron type universal tensile testing machine (manufactured by Toyo Seiki Co., Ltd., Stograph C type) Maximum load 100Kg/cm ² -5g/cm ² ●Tensile speed: 10mm/min ●Measurement temperature: 20±2℃ ●Measurement Humidity: 65%RH ●Specimen: No. 2 dumbbell type (thickness 1mm) ●Distance between gauge lines: 20mm ●Distance between grips: 70mm Elongation (E) and yield point strength (Y) under each of the above conditions ,
Strength at break (B): unirradiated, 200 hours, 400 hours, 800
Measurements were made for time and after 1200 hours of irradiation, respectively.
Furthermore, the residual rate of each physical property at each irradiation was calculated, and the results are summarized in Table 4.

【table】

[Table] From the results in Table 4, the following is a comparison of the residual rates of each physical property at each irradiation time. In the case of 200 hours of irradiation, the residual rate of E (%) No. 2 (105) > No. 3 (89) > No. 4
(85)≫No.1 (35) Remaining rate of Y (%) No.2 (100)≒No.3 (101)≒No.4
(100) > No. 1 (97) Remaining rate of B (%) No. 2 (109) > No. 1 (104) > No. 3
(99) = No. 4 (99) For 400 hours of irradiation, residual rate of E No. 3 (97) ≒ No. 2 (95) > No. 4 (85) ≫ N
o.
1 (10) Remaining rate of Y No. 2 (100) ≒ No. 3 (97) = No. 4 (97) Remaining rate of B No. 2 (104) > No. 3 (98) ≒ No. 4 ( 97)＞
No.
1 (88) In the case of 800 hours of irradiation, the residual rate of E No. 3 (97) > No. 2 (80) > No. 4 (70) >> N
o.
1 (0.7) Remaining rate of Y No. 3 (102) > No. 2 (99) > No. 4 (96) Remaining rate of B No. 3 (99) ≒ No. 2 (98) > No. 4 ( 96)≫N
o.
1 (29) In the case of 1200 hours of irradiation, the residual rate of E No. 3 (89) > No. 2 (69) > No. 4 (66) The residual rate of Y No. 3 (93) > No. 2 (90) > No. 4 (87) Remaining rate of B No. 2 (95) > No. 3 (90) > No. 4 (89) JISK-6732 (1981) “Remaining rate of elongation after accelerated weathering test (%) ” passes 50% to 60% or more for films with a thickness of 0.2 to 0.05 m/m, so if we evaluate No. 1 to No. 4 using this standard as a reference, No. 1: After 200 hours of irradiation. The residual rate of E is 35%, and it is judged that it is not suitable for use. Regarding Y and B, after 400 hours of irradiation, the hardening phenomenon or Y,
The classification of B becomes unclear. Therefore, it is determined that the No. 1 sample deteriorates and becomes unusable after 200 hours of irradiation. No. 2: E, Y, and B all showed good residual rates up to 400 hours of irradiation, and after 800 and 1200 hours of irradiation,
Next to No. 3, the remaining rate of E is 69%, and the remaining rate of Y is 90.
%, the residual rate of B was 95%, indicating that it could still be used. No. 3: After 1200 hours, the E residual rate was 89%, the highest value among all samples, and both Y and B had a residual rate of 90% or more.
It shows the best balanced physical properties among No. 1 to No. 4. No. 4: This sample is a sample with a conventional combination of weather-resistant PP, and the residual rate of E is 60% after 1200 hours, Y, B
It is also around 80%, which is lower than No. 2 and No. 3. Next, the results of considering the degree of yellowing, gloss, and degree of surface cracking after irradiation are as follows.

【table】

[Table] To make a comprehensive judgment on the above, the rutile type R- _TiO2 , which has been conventionally used as a weather resistance imparting agent for PPP.
It is clear that the ZnO/Zn-D-2EHDTPA mixture exhibits better weather resistance. Example 2 2(2'-hydroxy-5'-methylphenyl), the most commonly used ultraviolet absorber
Triazole (manufactured by Ciba Geigy, Tinuivin P
(Product name)) and samples No. 2 and No. 3 in Table 1 of Example 1, physical properties were measured (E, Y, B) when irradiated for 800 hours and 1200 hours. The results will be described. Furthermore, ZnO and Zn-D-2EHDTA
The mixed sample, PP formulation, test piece preparation conditions, weather resistance accelerated test conditions, physical property test conditions, etc. are as in Example 1.
According to.

[Table] Physical property test results of test pieces prepared according to Table 6 above, using the same injection molding machine as in Example 1, under the same conditions, and irradiated with Sunshine carbon arc lamp for 1200 hours. are shown in Table 7. However, the irradiation conditions and physical property tests were the same as in Example 1.

【table】

[Table] From the results shown in Table 7, the superiority and inferiority of each physical property and its residual rate after 800 hours and 1200 hours of irradiation are compared as follows. In the case of 800 hours of irradiation, residual rate of E (%) No. 2 (97) ≫ No. 4 (86) > No. 1
(82)≫No.3 (53) Remaining rate of Y (%) No.2 (102) > No.1 (99) > No.4
(97)≫No.3 (54) Remaining rate of B (%) No.2 (101) = No.4 (101) > No.1
(99)≫No.3 (62) Remaining rate of E (%) after 1200 hours of irradiation No.2 (92) > No.4 (88) > No.1 (7
Four)
≫No. 3 (30) Y remaining rate No. 2 (95) > No. 4 (92) > No. 1 (90) ≫ N
o.
3 (41) Remaining rate of B No. 2 (97) > No. (95) = No. 4 (95) ≫ No.
3
(52) As mentioned in Example 1, according to JIS-K-6732-1981, if the residual percentage of E is 50 to 60% or more, it is considered to be acceptable.
Time irradiation is the limit, and in the case of 1200 hours irradiation,
It will fail. However, in the case of blending 0.25 parts by weight of tinuibin, the results were second to No. 2 and were excellent. That is, it was found that by adding and blending ZnO/Zn-D-2EHDTA, the effect was equal to or greater than that of Tinuivin P. Example 3 This example uses No. 3 sample ZnO (wet method) in Table 1 in Example 1/Zn-D-2EHDTA=500g/
50g mixture to 100 parts by weight of PP, 5 parts by weight, 10
These are the test results when 15 parts by weight were mixed. Table 8 shows the blending amount for PP.

[Table] The blending conditions of ZnO/Zn-D-2EHDTA are the same as in Example 1. Further, the conditions for injection molding the mixtures shown in Table 8 to create JIS No. 2 dumbbell-shaped specimens (thickness 1 m/m) were also the same as in Example 1. The injection molded specimens were irradiated for 800 hours and 1200 hours using a Sunshine carbon arc lamp weathering tester.
The results are shown in Table 9. This weather resistance tester uses the same tester as in Example 1, and the conditions etc. are the same as in Example 1.

[Table] From the results in Table 9, no irradiation; 800 hours irradiation, 1200 hours
A comparison of the physical properties and residual rates of each time-irradiated specimen is as follows. In the case of non-irradiation, E (%) No. 1 No. 2 No. 3, and regarding elongation, those with 10 and 15 parts by weight are
30% or less, and 10% from additive-free specimen No. 1 in Table 4.
The sample (No. 2) with addition of 15 parts by weight decreased by about 30%, and the sample (No. 3) with 15 parts by weight addition decreased by 34%. Next, regarding Y and B in the case of non-irradiation, Y (Kgf/cm ² ): No. 2 > No. 3 > No. 1 B (Kgf/cm ² ): No. 3 > No. 2 > No. 1 No. 2 and No. 3, in which 10 and 15 parts by weight were added, showed higher values than No. 1, in which 5 parts by weight was added. That is, when added in an amount of 10 parts by weight or more, ZnO has a filler-like effect and particularly reduces elongation. In the case of irradiation for 800 hours, the residual percentages of E, Y, and B were between 93 and 102% for No. 1, No. 2, and No. 3, and it can be said that there was almost no change in any of them. In the case of 1200 hours of irradiation, the residual rates of E, Y, and B are almost the same for No. 1, No. 2, and No. 3, and although the residual rates are slightly lower than the 800 hour irradiation results, the values is more than 80%,
The Y residual rate of the No. 1 specimen showed only a decrease of 90% and the E residual rate of 80%, while each of the residual rates of the No. 2 and No. 3 specimens remained within about 6%. That is, ZnO/Zn-D-2EADTPA=100/
In the case of a mixing ratio of 5, adding 10 parts by weight or more does not seem to particularly increase the effect in the irradiation test. Example 4 In this example, ZnO produced by the wet method shown in Table 8 in Example 3 was replaced with ZnO produced by the dry method, and all other conditions were the same as in Example 3. I did this. The results are shown in Table 10.

[Table] ZnO produced by dry method (hereinafter referred to as D-ZnO)
and ZnO produced by a wet method (hereinafter referred to as W-ZnO)
Comparison of mixing effects when using (Tables 9 and 10)
(You can compare it with the table), then you get the following. ●Unirradiated E (%) is D-ZnO>W-ZnO in any case of addition of 5 to 15 parts by weight, Y, B
(Kgf/cm ² ), when 10 to 15 parts by weight is added, W-ZnO is slightly better. ●Remaining rate after 800 hours of irradiation is W-ZnO, D
In the case of -ZnO, E, Y, and B all show values of 90% or more, but W-ZnO>D-ZnO. In the case of irradiation for 1200 hours, comparing each E, Y, and B, the values for D-ZnO are 83 to 92%, and the values for W-ZnO are 89 to 95%. It can be seen that -ZnO>D-ZnO. In other words, it was found that W--ZnO showed better results than D--ZnO. Judging from the above examples, ZnO/Zn-D-
When 2HDTPA is mixed and blended, as ZnO,
The effect of W-ZnO is greater than that of D-ZnO, and the effect is saturated even if added in an amount of 10 parts by weight or more, but the effect up to 10 parts by weight is It is clear that -TiO ₂ is more pronounced than Tinuibin-P.

Claims (1)

[Scope of Claims] 1. A polypropylene composition comprising a weather resistance imparting agent consisting of a mixed system of zinc oxide and zinc di-2-ethylhexyldithiophosphate. 2 The amount of the weather resistance imparting agent added is 2.0 to 10.0 parts by weight of zinc oxide and 0.1 to 2.5 parts by weight of zinc di-2-ethylhexyl dithiophosphate per 100 parts by weight of polypropylene. 1
The polypropylene composition described in . 3. The polypropylene composition according to claim 1 or 2, wherein the zinc oxide is zinc oxide obtained by a wet method. 4. The polypropylene composition according to claim 1 or 2, wherein the zinc oxide is zinc oxide obtained by a melting method.