JPH0716967B2 - Hard vinyl chloride resin pipe fitting - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hard vinyl chloride resin pipe joint, more specifically, mechanical properties such as impact strength and tensile strength, heat distortion resistance, and weather resistance. The present invention relates to a pipe joint made of a hard vinyl chloride resin having excellent properties.

[Prior Art] A pipe (rigid pipe) made of a hard vinyl chloride resin has a high degree of polymerization of vinyl chloride resin, for example, an average degree of polymerization of 900 to 105
It is manufactured by extrusion molding 0 resin.

On the other hand, a pipe joint made of a hard vinyl chloride resin is generally manufactured by injection molding. Compared with extrusion molding, injection molding requires a higher fluidity of the molten resin because the molten vinyl chloride resin flows into the mold at a higher speed.

However, if a high vinyl chloride resin with a high degree of polymerization, which is used for extrusion molding of tubes, is used for injection molding, the flowability of the molten resin is low, making injection molding extremely difficult or impossible. Becomes If the molding temperature is increased to improve the fluidity of the molten resin, the thermal decomposition temperature of the hard vinyl chloride resin is relatively low at around 200 to 210 ° C., so that it easily decomposes during molding.

If a vinyl chloride resin composition with excessive addition of a lubricant or a plasticizer is used to improve fluidity, the heat distortion resistance and weather resistance of the pipe joint obtained by injection molding will decrease, and Satisfactory performance cannot be obtained.

Therefore, for injection molding, a low polymerization degree hard vinyl chloride resin having an average polymerization degree of 800 or less is usually used alone. However, when such a vinyl chloride resin with a low degree of polymerization is used, mechanical strength such as impact strength of an injection molded pipe joint, heat distortion resistance, and weather resistance are significantly reduced, and cracking occurs when used for a long time. It is easy to be damaged by such things as. On the other hand, since the pipe and the pipe joint made of the hard vinyl chloride resin are used under the same condition, the low durability of the pipe joint made of the hard vinyl chloride resin lowers the overall durability.

Conventionally, as a method for solving this problem, for example,
58-38306 uses a vinyl chloride resin with an average degree of polymerization of 1000 or higher and a vinyl chloride resin with an L / D of 25 or more, and a heating cylinder temperature of 17
Adjusting to 5 to 185 ℃, melt-kneading the molding material, etc.
It has been proposed to improve the injection molding process to produce pipe fittings. However, even with this method, there is a problem that the resin staying at the tip of the cylinder deteriorates in long-term continuous injection molding, and its industrial utility is small.

Further, a method of adding an impact modifier to improve the impact resistance of the vinyl chloride resin is generally adopted. However, when the impact modifier is added, the melt viscosity of the resin increases, so that The fluidity becomes low, which makes injection molding difficult, and further causes deterioration in heat distortion resistance.

[Problems to be Solved by the Invention]

The object of the present invention is to provide a pipe joint having mechanical properties such as impact strength, heat deformation resistance, and weather resistance equivalent to those of a high polymerization degree hard vinyl chloride resin pipe produced by extrusion by injection molding. To provide.

The present inventor, as a result of intensive studies to overcome the problems of the above-mentioned prior art, a vinyl chloride resin having a high average degree of polymerization and a vinyl chloride resin having a low average degree of polymerization, the average polymerization of a mixed resin. By using a vinyl chloride resin whose degree of polymerization is within the range of the average degree of polymerization of the vinyl chloride resin used to create a rigid pipe by ordinary extrusion molding, it has good injection moldability and excellent physical properties. The present invention has been completed based on the finding that a pipe joint can be obtained.

[Means for Solving the Problems]

Thus, according to the present invention, an average degree of polymerization of vinyl chloride resin having an average degree of polymerization of 950 to 1100 is 50 to 95 parts by weight, and an average degree of polymerization of vinyl chloride resin having an average degree of polymerization of 500 to 900 is 5 to 50 parts by weight.
Vinyl chloride resin composition 1 mixed in a range of 0
A hard vinyl chloride resin pipe joint is provided which is obtained by injection-molding a resin composition containing 00 parts by weight and an impact modifier of 0 to 30 parts by weight.

Hereinafter, the present invention will be described in detail.

(Vinyl chloride resin) In the present invention, as a hard vinyl chloride resin for injection molding, a vinyl chloride resin having an average degree of polymerization of 950 to 1100, preferably 1000 to 1050 (hereinafter, abbreviated as high degree of polymerization PVC) , A mixed resin with an average degree of polymerization of 500 to 900, preferably 600 to 800 vinyl chloride resin (hereinafter, abbreviated as low degree of polymerization PVC), and the average degree of polymerization of the mixed resin is in the range of 900 to 1000. A vinyl chloride resin is used.

As the high polymerization degree PVC and the low polymerization degree PVC, a homopolymer of a vinyl chloride monomer or a copolymer of a vinyl chloride monomer and another monomer copolymerizable therewith, or a combination thereof is used. Things are used.

Other monomers that can be copolymerized with the vinyl chloride monomer include
For example, α-olefins such as ethylene and propylene;
Vinyl esters such as vinyl acetate, vinyl propionate and vinyl stearate; unsaturated carboxylic acids such as acrylic acid; unsaturated nitriles such as acrylonitrile; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinylidene chloride such as vinylidene chloride; And so on.

High degree of polymerization PVC average polymerization degree 950 ~ 1100, preferably 1000
~ 1050 is generally because a hard tube is manufactured by extrusion molding using a vinyl chloride resin having an average degree of polymerization in this range, and by using this high degree of polymerization PVC as a blending component. This is to impart mechanical properties such as impact strength, heat distortion resistance, and weather resistance equivalent to those of a hard pipe to a pipe joint manufactured by injection molding.

On the other hand, the average degree of polymerization of the low degree of polymerization PVC is 500 to 900, preferably 600 to 800, because the vinyl chloride resin having an average degree of polymerization of less than 500 gives an impact even when blended with the high degree of polymerization PVC. This is because mechanical properties such as strength and impact strength after long-term use are significantly reduced. Conversely, when a vinyl chloride resin having an average degree of polymerization of more than 900 is used, the fluidity of the molten resin can be increased. It will be difficult.

In the present invention, as the vinyl chloride resin, a high degree of polymerization PVC50
~ 95 parts by weight, preferably 60-90 parts by weight, low polymerization degree PVC5
To 50 parts by weight, preferably 10 to 40 parts by weight, and
A vinyl chloride resin composition having an average degree of polymerization of 900 to 1000 is used.

If the proportion of the high degree of polymerization PVC is too low, the mechanical strength, heat resistance and weather resistance are lowered, and if it is too high, the fluidity of the molten resin is not improved and injection molding becomes difficult or impossible. In addition, the average degree of polymerization of the resin composition obtained by mixing the two is within the above range, so that injection moldability is possible and good, and mechanical strength is higher than that when a high degree of polymerization resin alone is used. Good heat resistance and weather resistance. Therefore, a pipe joint having the same physical properties as a general hard pipe can be obtained by injection molding. If the average degree of polymerization of the vinyl chloride resin composition is less than 900, the mechanical strength, heat resistance and weather resistance will be insufficient, and if it exceeds 1000, injection molding will be difficult.

(Optional component) The vinyl chloride resin composition of the present invention includes a stabilizer, a lubricant,
Conventional additives for vinyl chloride resins such as colorants may be appropriately mixed.

Further, in the present invention, the impact resistance is improved by adding the impact modifier in the vinyl chloride resin composition in an amount of 30 parts by weight or less, preferably 5 to 30 parts by weight, more preferably 7 to 15 parts by weight. It is possible to improve the sex. As the impact resistance improver, known impact resistance improvers can be used.
For example, acrylic rubber, ABS resin, MBS resin, ethylene-
Examples thereof include vinyl acetate copolymer (EVA) and chlorinated polyethylene. If the compounding ratio of the impact resistance improver exceeds 30 parts by weight, the melt fluidity is deteriorated and the heat distortion resistance is also deteriorated. Depending on the application in which the pipe joint is used, the impact modifier may not be used, and the presence or absence of the compound or the amount thereof is appropriately selected depending on the purpose of use.

The hard vinyl chloride resin pipe joint of the present invention has a high degree of polymerization PV
A vinyl chloride resin composition prepared by mixing C and PVC with a low degree of polymerization to an average degree of polymerization of 900 to 1000, if desired, a stabilizer, a lubricant, a colorant, an impact modifier, and the like in appropriate amounts, and Henschel. It can be produced by uniformly mixing the mixture using a mixer or the like by a conventional method and injection-molding the obtained hard vinyl chloride resin composition.

〔Example〕

Next, examples of the present invention will be shown, but the present invention is not limited to the following examples.

In Example 1 and Comparative Examples 1 to 5, hard vinyl chloride resin compositions were produced by mixing and kneading the respective components by a conventional method according to the formulation shown in Table 1.

As a vinyl chloride resin, Kyodo Vinyl Sales Co., Ltd. has a high polymerization degree PVC with an average degree of polymerization of 1030 (trade name: Kyodo Vinyl S
L), Kyodo Vinyl Sales Co., Ltd. has a low degree of polymerization of 800
PVC (trade name: Kyodo Vinyl SR), Kyodo Vinyl Sales Co., Ltd.
PVC with an average degree of polymerization of 700 (trade name: Kyodo Vinyl S
E), low polymerization degree PVC (product name: Kyodo Vinyl SG) with an average polymerization degree of 650 of Kyodo Vinyl Sales Co., Ltd. and low polymerization degree PVC (product name: Nipolit S) of an average polymerization degree 450 of Chisso Co., Ltd. -450) was used.

MBS manufactured by Mitsubishi Rayon Co., Ltd. as an impact resistance improver
A toughening agent (trade name: Metabrene-223) was used.

The methods for measuring the physical properties are as follows.

Melt flow is 210 ° C according to JIS K7210, method A,
The measurement was performed under the conditions of a load of 10 kg, preheating for 5 minutes, and L / D = 8/2.

In addition, the resin compositions obtained in Example 1 and Comparative Examples 1 to 5 were injection-molded by two kinds of injection molding machines (L / D = 22 and 28) having different screws L / D to obtain. Vicat softening temperature, tensile strength, and Izod impact strength before and after weatheraro exposure were measured by injection molding test pieces.

The Vicat softening temperature test is based on JIS K7206,
It was measured under the conditions of Method A and a temperature rising rate of 50 ° C./hour, and the tensile strength and Izod impact strength were measured at 23 ° C. and 0 ° C. according to JIS K6740, respectively. Weatheraro exposure is 63
℃ It was carried out for 100 hours under the condition of rain.

Injection molding conditions are screw diameter 40mm, L / D = 22 and 2
8, heating cylinder temperature 195 ℃ (metering zone),
The speed ratio (cavity part / runner part) was 1.3.

The injection moldability was evaluated according to the following four grades.

⊚: Very good, ◯: Good, Δ: Inferior ×: Unmoldable.

Further, as the long-run formability, the time when the test piece was burnt was measured when the long-run operation was performed.

[Example 1] In order to see the effect of the present invention, as a high degree of polymerization PVC, Kyodo Vinyl Sales Co., Ltd. has an average degree of polymerization of 1030
SL was 75% by weight and low polymerization degree PVC was mixed by mixing Kyodo Vinyl SR Co., Ltd. with an average polymerization degree of 800 and a mixing degree of 25% by weight, and the average polymerization degree was adjusted to 970. The product was used as 100 parts by weight of vinyl chloride resin.

Various compounding agents shown in Table 1 were added to this vinyl chloride resin composition to prepare a resin composition, which was then injection molded.

An injection molding machine having a screw L / D of 22 was used.

[Example 2] In order to see the effect of the present invention, as a high degree of polymerization PVC, Kyodo Vinyl Co., Ltd. has an average degree of polymerization of 1030.
SL was 85% by weight and low polymerization degree PVC was mixed with Kyodo Vinyl Sales Co., Ltd. with an average polymerization degree of 700 and Kyodo Vinyl SE was mixed at a ratio of 15% by weight to adjust the average polymerization degree to 980. The product was used as 100 parts by weight of vinyl chloride resin.

An injection molding machine having a screw L / D of 22 was used.

[Example 3] In order to see the effect of the present invention, as a high degree of polymerization PVC, Kyodo Vinyl Co., Ltd. has an average degree of polymerization of 1030
SL was 85% by weight and low polymerization degree PVC was mixed with Kyodo Vinyl Sales Co., Ltd. which had an average degree of polymerization of 650 and was mixed with Kyodo vinyl SG at a rate of 15% by weight so that the average degree of polymerization was 970. The product was used as 100 parts by weight of vinyl chloride resin.

An injection molding machine having a screw L / D of 22 was used.

[Example 4] In order to see the effect of the present invention, as a high degree of polymerization PVC, Kyodo Vinyl Sales Co., Ltd. has an average degree of polymerization of 1030
SL was 70% by weight and low polymerization degree PVC was mixed with Kyodo Vinyl Sales Co., Ltd., which had an average polymerization degree of 700 and was mixed with Kyodo Vinyl SE at a ratio of 30% by weight, so that the average polymerization degree was 930. The product was used as 100 parts by weight of vinyl chloride resin.

An injection molding machine having a screw L / D of 22 was used.

[Comparative Example 1] As 100 parts by weight of vinyl chloride-based resin, Kyodo Vinyl SR Co., Ltd. having an average degree of polymerization of 800 was used.

An injection molding machine having a screw L / D of 22 was used.

[Comparative Example 2] As 100 parts by weight of vinyl chloride resin, Kyodo Vinyl SL having an average degree of polymerization of 1030 manufactured by Kyodo Vinyl Sales Co., Ltd. was used.

An injection molding machine having a screw L / D of 22 was used.

Comparative Example 3 As 100 parts by weight of the vinyl chloride resin, Kyodo Vinyl SL having an average degree of polymerization of 1030 manufactured by Kyodo Vinyl Sales Co., Ltd. was used.

An injection molding machine having a screw L / D of 28 was used.

[Comparative Example 4] As a high degree of polymerization PVC, 90% by weight of Kyodo Vinyl SL having an average degree of polymerization of 1030 of Kyodo Vinyl Sales Co., Ltd. and a low degree of polymerization PV
As C, Nipolit S-450 having an average degree of polymerization of Chisso Corporation of 450 was mixed at a ratio of 10% by weight to obtain an average degree of polymerization of 9
The product adjusted to 70 was used as 100 parts by weight of vinyl chloride resin.

An injection molding machine having a screw L / D of 28 was used.

[Comparative Example 5] As 100 parts by weight of vinyl chloride resin, Kyodo Vinyl SL (Kyoto Vinyl Sales Co., Ltd.) having an average degree of polymerization of 1030 was used, and the compounding was performed without adding an impact modifier.

An injection molding machine having a screw L / D of 28 was used.

[Comparative Example 6] As 100 parts by weight of vinyl chloride resin, Kyodo Vinyl SL having an average degree of polymerization of 1030 of Kyodo Vinyl Sales Co., Ltd. was used, and 3 parts by weight of a plasticizer was added.

An injection molding machine having a screw L / D of 28 was used.

[Comparative Example 7] As a high degree of polymerization PVC, Kyodo Vinyl Sales Co., Ltd. has 50% by weight of Kyodo Vinyl SL having an average degree of polymerization of 1030 and a low degree of polymerization PVC.
As a vinyl chloride resin 100, Kyodo Vinyl Sales Co., Ltd. mixed Kyodo Vinyl SE with an average degree of polymerization of 700 at a ratio of 50% by weight and adjusted so that the average degree of polymerization was 870.
Used as parts by weight.

An injection molding machine having a screw L / D of 22 was used.

[Comparative Example 8] As a high degree of polymerization PVC, 95% by weight of Kyodo Vinyl SL having an average degree of polymerization of 1030 of Kyodo Vinyl Sales Co., Ltd., a low degree of polymerization PVC
As a vinyl chloride resin, a mixture of Kyodo Vinyl SE with an average degree of polymerization of 700 from Kyodo Vinyl Sales Co., Ltd. was mixed at a ratio of 5% by weight, and the average degree of polymerization was adjusted to 1010.
Used as 0 parts by weight.

An injection molding machine having a screw L / D of 22 was used.

The results are collectively shown in Table 1.

As is clear from the results in Table 1, Examples 1 to 4 are superior to Comparative Example 1 in tensile strength and Izod impact strength, and superiority due to high average degree of polymerization was found. It was

Further, in Comparative Example 2, injection molding could not be performed because the molten resin had poor fluidity as compared with Examples 1 to 4.
From this, the effect of increasing the fluidity of the molten resin by mixing the vinyl chloride resins having low average degrees of polymerization in Examples 1 to 4 was recognized. Comparative Example 3 is Examples 1 to 4.
Compared with, the physical properties are not inferior, but the long-run moldability is extremely inferior, and therefore has no industrial utility. Comparative Example 4 uses a vinyl chloride resin having an average degree of polymerization of 450 as the low polymerization degree vinyl chloride resin as compared with Examples 1 to 4, so that the Izod impact strength value after weathering is significantly reduced. did.

Further, in Comparative Example 5, the impact strength was remarkably reduced as compared with Examples 1 to 4. Further, Comparative Example 6 is Examples 1 to 4.
The tensile strength and the Picut softening point were decreased in comparison with.

Although Comparative Example 7 has slightly improved physical properties as compared with Comparative Example 1,
Compared with Examples 1 to 4, the average degree of polymerization was slightly lower, and therefore physical properties equivalent to those of Examples 1 to 4 were not exhibited. Similarly, Comparative Example 8 has a slightly higher average degree of polymerization as compared with Examples 1 to 4, so that the effect of improving melt fluidity becomes small,
It is considered that the long-run moldability was deteriorated.

From the above, the average degree of polymerization is 950 to 1100, preferably 1
The average degree of polymerization of vinyl chloride resin of 0000 to 1050 is 500 to
By mixing the vinyl chloride resin, which is 900, preferably 600 to 800, to increase the fluidity of the molten resin,
It is considered that a hard vinyl chloride resin pipe joint manufactured by injection molding having mechanical properties such as impact strength equivalent to an average degree of polymerization of 1000, heat deformation resistance, and weather resistance could be obtained.

[Effects of the Invention] According to the present invention, mechanical properties such as impact strength and tensile strength, heat distortion resistance, and weather resistance equivalent to those of a high polymerization degree hard vinyl chloride resin pipe manufactured by extrusion molding. A pipe joint having is provided by injection molding.

Claims (1)

[Claims] 1. A vinyl chloride resin 5 having an average degree of polymerization of 950 to 1100.
0 to 95 parts by weight, 100 parts by weight of a vinyl chloride resin composition obtained by mixing 5 to 50 parts by weight of a vinyl chloride resin having an average degree of polymerization of 500 to 900 so that the average degree of polymerization is in the range of 900 to 1000,
A hard vinyl chloride resin pipe joint, which is obtained by injection-molding a resin composition containing 0 to 30 parts by weight of an impact resistance improver.