JP5367456B2 - Rigid polyvinyl chloride resin composition for injection molding and use thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rigid vinyl chloride resin composition for injection molding in which a recycled vinyl chloride resin is used, and which has good suitability to kneading and gives an injection molded body having good appearance. <P>SOLUTION: The rigid vinyl chloride resin composition for injection molding contains: 35-80 pts.wt. of a recycled raw material A comprising a rigid vinyl chloride resin composition based on a vinyl chloride resin having an average polymerization degree of 900-1,200 or a pulverized product of the recycled raw material A; 10-50 pts.wt. of a vinyl chloride resin B having an average polymerization degree of 560-850; 3-25 pts.wt. of a vinyl chloride resin C having an average polymerization degree of 450-550; and 1-15 pts.wt. of a stabilizer, wherein the total amount of the recycled raw material A, the vinyl chloride resin B and the vinyl chloride resin C is 100 pts.wt. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to a hard vinyl chloride resin composition for injection molding. Specifically, the present invention relates to a hard vinyl chloride resin composition for injection molding containing a recycled vinyl chloride resin and an unused vinyl chloride resin as main components. In particular, the present invention relates to the above composition, wherein the recycled vinyl chloride resin is an extruded hard vinyl chloride resin.

A rigid vinyl chloride resin composition for injection or extrusion containing a recycled vinyl chloride resin and an unused vinyl chloride resin as main components is known (Patent Documents 1 and 2). Moreover, the hard vinyl chloride resin composition containing two types of unused vinyl chloride resins of different average polymerization degrees is also known (patent documents 3-6).

JP 2007-277396 A Japanese Patent Laid-Open No. 06-329859 Japanese Patent Laid-Open No. 60-223847 Japanese Examined Patent Publication No. 59-028342 Japanese Patent Publication No. 07-016967 JP 2008-120852 A

When the extruded hard vinyl chloride resin is reused for injection molding, there are problems such as poor appearance of the resulting molded article. This is because the average degree of polymerization of a vinyl chloride resin suitable for extrusion molding is generally larger than the average degree of polymerization suitable for injection molding, and the fluidity is small.
There is known a hard vinyl chloride resin composition for injection molding composed of a recycled vinyl chloride resin having a relatively high average degree of polymerization and a vinyl chloride resin having a relatively low average degree of polymerization (Patent Document 1). Since the kneadability of the composition is poor and the resulting molded article may have a poor appearance, its use is limited.
An object of the present invention is to provide a hard vinyl chloride resin composition for injection molding in which a recycled vinyl chloride resin is used, which gives an injection-molded article with good kneadability of the composition and good appearance.

In order to solve the above-mentioned problem, the hard vinyl chloride resin composition for injection molding according to claim 1 is
35-80 parts by weight of recycled material A or ground material of recycled material A comprising a hard vinyl chloride resin composition whose main component is a vinyl chloride resin having an average degree of polymerization of 900-1200,
10 to 50 parts by weight of vinyl chloride resin B having an average degree of polymerization of 560 to 850,
Containing 3-25 parts by weight of vinyl chloride resin C having an average degree of polymerization of 450-550, and 1-15 parts by weight of stabilizer D,
The total amount of recycled raw material A, vinyl chloride resin B and vinyl chloride resin C is 100 parts by weight.

The rigid vinyl chloride resin composition for injection molding according to the invention described in claim 2 is characterized in that it contains 2 to 20 parts by weight of the impact modifier E in the composition described in claim 1.
A rigid vinyl chloride resin composition for injection molding according to a third aspect of the present invention is characterized in that in the composition according to the first or second aspect, the stabilizer D is a lead compound.
A rigid vinyl chloride resin composition for injection molding according to a fourth aspect of the invention is characterized in that, in the composition according to the third aspect, the reuse raw material A contains a lead compound.
The hard vinyl chloride resin composition for injection molding of the invention according to claim 5 is the composition according to any one of claims 2 to 4, wherein the impact modifier E contains an acrylate polymer. It is characterized by being.

The method for producing a hard vinyl chloride resin composition for injection molding of the invention according to claim 6 comprises:
Process 1 for pulverizing recycled material A to produce pulverized product V,
Comprising a step 2 for producing a raw material mixture W by mixing raw materials other than the recycled raw material A and a pulverized product V; and a step 3 for producing a pellet X by heating and kneading the raw material mixture W with an extruder.
It is a method of manufacturing the composition of Claims 1-5.

A method for producing a molded body comprising the hard vinyl chloride resin composition for injection molding of the invention according to claim 7,
Process 1 for pulverizing recycled material A to produce pulverized product V,
Step 2 of mixing raw materials other than the recycled raw material A and the pulverized product V to produce a raw material mixture W,
A step 3 in which the raw material mixture W is heated and kneaded by an extruder to produce a pellet X, and a step 4 in which the pellet X is injection molded by an injection molding machine to produce a molded body Y.
It is a method of manufacturing the molded object which consists of a composition of Claims 1-5.

The invention according to claim 8 is obtained by the method according to claim 7.
The joint according to the ninth aspect is obtained by the method according to the seventh aspect.
The invention according to claim 10 comprises the rigid vinyl chloride resin composition for injection molding according to claims 1-5.
A joint according to an eleventh aspect of the present invention comprises the rigid vinyl chloride resin composition for injection molding according to any one of the first to fifth aspects.

The waste material of vinyl chloride resin could be used effectively as a recycled material. The composition had good kneadability, and the resulting molded product had a good appearance.

In the present specification, when the numerical range is indicated by “lower limit numerical value to upper limit numerical value”, it means that the numerical value range is not less than the lower limit value and not more than the upper limit value.
The average degree of polymerization is measured according to JIS K6720-2.
Further, the term “hard” means that the tensile elastic modulus is 100,000 psi (7000 kgf / cm ² ) or more.
First, the composition of the present invention will be described in the order of the reusable raw material A, vinyl chloride resin B, vinyl chloride resin C, etc., which are the main components. Subsequently, manufacture of a composition, manufacture of a molded object, evaluation, etc. are demonstrated.

  The reuse raw material A is composed of a hard vinyl chloride resin composition whose main component is a vinyl chloride resin having an average degree of polymerization of 900 to 1200. Reuse in this specification means narrow reuse (for example, a molded product distributed and used in the market or a molded product transferred from a manufacturer to a third party is used after being pulverized) and regeneration (for example, It is understood in a broad sense including chopped-off products in the manufacturer's company or out-of-specification molded bodies being used after being crushed.

The recycle raw material A cannot always be obtained with the same composition because of the nature of recycle, but a recycle material A that satisfies certain conditions is used.
The rigid polyvinyl chloride resin pipe for water supply / drainage is a main raw material supply source of the recycled raw material A. The pipe is usually manufactured by extrusion molding of a hard vinyl chloride resin composition mainly composed of a vinyl chloride resin having an average degree of polymerization of 900 to 1200. The molded body represented by the pipe is used after being pulverized to an appropriate size as described later.
As the recycle raw material A, a material mainly composed of a vinyl chloride resin having an average degree of polymerization of 950 to 1150 is preferred, and a material mainly comprising a vinyl chloride resin having an average degree of polymerization of 1000 to 1100 is more preferred.

In addition to the vinyl chloride resin, the reusable raw material A usually contains about several percent of a stabilizer and a lubricant.
When the stabilizer D described later is a lead compound, it is preferable that the recycle raw material A contains a lead compound as a stabilizer for preventing sulfide contamination and for a high stabilizing effect.
The recycled material A is preferably substantially free of a plasticizer. “Not substantially contained” means that the content is 10% or less, preferably 7% or less, more preferably 5% or less.

The vinyl chloride resin B is a vinyl chloride resin having an average degree of polymerization of 560 to 850.
The vinyl chloride resin C is a vinyl chloride resin having an average degree of polymerization of 450 to 550.
When the vinyl chloride resins B and C are used in combination with the recycle raw material A at a specific ratio, the composition has good kneadability and the resulting molded article has good appearance.

The ratio of each component based on 100 parts by weight of the total amount of the recycled raw material A, the vinyl chloride resin B, and the vinyl chloride resin C is as follows.
The ratio of the reuse raw material A is 35 to 80 parts by weight, preferably 40 to 75 parts by weight, and more preferably 45 to 72 parts by weight.
The ratio of the vinyl chloride resin B is 10 to 50 parts by weight, preferably 13 to 45 parts by weight, and more preferably 17 to 42 parts by weight.
The ratio of the vinyl chloride resin C is 3 to 25 parts by weight, preferably 4 to 20 parts by weight, and more preferably 5 to 18 parts by weight.

  If the ratio of the reused raw material A is too small, the resulting molded product tends to have insufficient heat resistance and tensile strength, and the effect of resource saving and energy saving due to reuse of waste materials is diminished. When there are too many ratios of the reuse raw material A, the molded object obtained will become a thing with a bad external appearance.

  When the ratio of the vinyl chloride resin B is too small, the composition has poor kneadability and the resulting molded product has poor appearance. When the ratio of the vinyl chloride resin B is too large, the resulting molded product tends to be insufficient in heat resistance and tensile strength, and the effect of resource saving and energy saving due to reuse of waste materials is diminished.

  If the proportion of the vinyl chloride resin C is too small, the composition has poor kneadability and the resulting molded product has poor appearance. If the proportion of the vinyl chloride resin C is too large, the resulting molded product tends to be insufficient in heat resistance and tensile strength, and the effect of resource saving and energy saving due to reuse of waste materials is diminished.

  When the reused raw material A is used for injection molding as it is, the resulting molded product has a poor appearance. Most of the reused raw material A has an extrusion molding specification, and a vinyl chloride resin having a relatively large average polymerization degree is mainly used. This is considered to be because the fluidity is small because it is a component and it is difficult to form a uniform melt in the injection molding machine. The injection molding machine is considered to give such a result because the shear stress applied to the contents is smaller than that of the extrusion molding machine.

  Since the vinyl chloride resin B and the vinyl chloride resin C having a relatively low average degree of polymerization give a composition that tends to be a uniform melt due to a relatively small shear stress, the effect of improving the kneadability of the composition is exhibited and obtained. It is thought that the effect which makes the external appearance of a molded object favorable is expressed.

  As a vinyl chloride resin having a relatively low average degree of polymerization, the use of either vinyl chloride resin B or vinyl chloride resin C is insufficient for the above effect, and vinyl chloride resin B and vinyl chloride resin C may be used in combination. is important. The reason is presumed as follows.

  Since the vinyl chloride resin B has an average degree of polymerization relatively close to that of the vinyl chloride resin having an average degree of polymerization of 900 to 1200, which is the main component of the recycled material A, the two are easily compatible with each other. It seems that it contains an element that tends to improve the kneadability. However, since vinyl chloride resin B is not extremely small in average polymerization degree, it seems that the effect of improving the kneadability of the composition is small.

  On the other hand, since the vinyl chloride resin C has a very small average degree of polymerization, it is likely to include elements that tend to improve the fluidity of the composition and improve the kneadability of the composition. However, since vinyl chloride resin C has a relatively large difference in average degree of polymerization from vinyl chloride resin, which is the main component of recycled raw material A, both are not compatible with each other, and the kneadability of the composition is difficult to improve. It seems that it has become.

  As a vinyl chloride resin having a relatively low average degree of polymerization, by using a combination of vinyl chloride resin B and vinyl chloride resin C in a specific ratio, the respective advantages work synergistically, and the kneadability of the composition is particularly good. Thus, it is presumed that the resulting molded product has a particularly excellent appearance.

The stabilizer D is a component mainly for preventing the vinyl chloride resin from being decomposed at high temperatures, and reduces discoloration, deterioration of the composition, corrosion of the molding machine, etc. in the kneading process and molding process of the composition. . As the stabilizer D, those known as stabilizers for vinyl chloride resins can be used. As stabilizer D, lead compounds such as tribasic lead sulfate, dibasic lead phosphite, basic lead sulfite, dibasic lead phthalate, dibasic lead stearate, lead stearate, alkyl tin mercaptides, etc. Mercapto tin compounds, malate tin compounds such as alkyl tin malates, and those known as Ca / Zn stabilizers.
Lead compounds are preferred stabilizers because of their excellent stabilization effect.
The ratio of the stabilizer D based on 100 parts by weight of the total amount of the recycled raw material A, vinyl chloride resin B and vinyl chloride resin C is 1 to 15 parts by weight, and preferably 2 to 10 parts by weight.

  The composition of the present invention contains reused raw material A or a pulverized product of recycled raw material A, vinyl chloride resin B, vinyl chloride resin C, and stabilizer D in a predetermined ratio.

The composition of the present invention may contain an impact modifier E in addition to the above essential components. Examples of the impact modifier E include core-shell particles having a rubber component as a core and a methyl methacrylate copolymer as a shell. A rubber component in which styrene butadiene rubber or butadiene rubber is used (MBS) or an acrylic rubber made of an acrylate polymer is a typical impact resistance modifier.
A modifier (acrylic rubber-based modifier) in which an acrylic rubber made of an acrylate polymer is used as a rubber component is a preferable impact modifier for the present invention in order to improve the kneadability of the composition. is there.
The ratio of the impact modifier E based on 100 parts by weight of the total amount of the recycled material A, vinyl chloride resin B and vinyl chloride resin C is 2 to 20 parts by weight, and preferably 4 to 15 parts by weight.

The composition of the present invention may be added with a lubricant, a stabilizing aid, an antioxidant, a processing aid, a pigment, and other additives.
The composition of the present invention contains substantially no plasticizer.

Next, the production method of the composition will be exemplified and described. The method comprising the following steps 1, 2 and 3 is a preferred method for producing the composition.
As the pretreatment in step 1, it is preferable that foreign matters are removed by cleaning the reuse raw material A or the like.

Step 1 is a step of manufacturing the pulverized product V by pulverizing the reused raw material A. The pulverization in the present invention includes concepts such as crushing and crushing, and is not necessarily limited to crushing until it becomes powder. The size of the pulverized product V is preferably 10 mm or less in diameter or long side, more preferably 7 mm or less, and still more preferably 5 mm or less. If the pulverized product is too large, the subsequent steps may not be performed smoothly. The lower limit of the size of the pulverized product is not particularly limited, but is preferably 0.01 mm or more, and more preferably 0.05 mm or more. Even if it is made finer than necessary, it is not only useless, but the handling workability may worsen.
For the pulverization, a known pulverizer, crusher, crusher, etc. can be used.

  Step 2 is a step of manufacturing a raw material mixture W by mixing raw materials other than the reused raw material A (vinyl chloride resin B, vinyl chloride resin C, stabilizer D, etc.) and a pulverized product V. A known mixer can be used for mixing.

Step 3 is a step of manufacturing the pellet X by heating and kneading the raw material mixture W with an extruder.
A mesh is preferably attached to the flow path of the molten composition in the extruder. The mesh attachment is effective for removing foreign substances derived from the reused raw material A that could not be removed.
When the kneadability of the composition is good, the throughput per unit time of the process can be increased, and the productivity becomes good.

  Next, the manufacturing method of a molded object is illustrated and demonstrated. The method comprising the above steps 1, 2 and 3 and the following step 4 is a preferable method as a method for producing a molded article.

Step 4 is a step of manufacturing the molded body Y by injection molding the pellet X with an injection molding machine.
When the kneadability of the composition is good, a molded article having a good appearance can be easily obtained.

Although there is no restriction | limiting in particular in the use of a molded object, It can use suitably as a material for water supply / drainage equipment. Fittings such as small-diameter manholes, public masers, drainers, and sewage fittings are particularly suitable applications.

(material)
The raw materials used are as follows.
1. Recycled raw material A
-Recycled raw material A1: Recycled material of rigid PVC pipes or rigid PVC joints transferred from the association of polyvinyl chloride pipes and joints (extruded product, average polymerization degree of vinyl chloride resin 1050)
2. Vinyl chloride resin B
・ Vinyl chloride resin B1: Vinyl chloride resin powder (average polymerization degree 800)
Vinyl chloride resin B2: Vinyl chloride resin powder (average polymerization degree 680)
・ Vinyl chloride resin B3: Vinyl chloride resin powder (average polymerization degree 600)
3. Vinyl chloride resin C
・ Vinyl chloride resin C1: Vinyl chloride resin powder (average polymerization degree 500)
4). Stabilizer D
Stabilizer D1: Stabilizer comprising a lead compound Impact resistance modifier E
・ Modifier E1: Acrylic rubber-based modifier6. Other additives / additives F1: Lubricants / additives F2: Processing aid (methyl methacrylate polymer)
Additive F3: Pigment

(Production of composition)
1. Process 1
The reused raw material A1 from which foreign matters were removed by washing with water in advance was pulverized by a pulverizer. The pulverized product V that passed through a 6 mm mesh wire mesh was collected.
2. Process 2
The raw material mixture W was manufactured by mixing the raw materials described in Table 1 with a mixer.
3. Process 3
The raw material mixture W was heated, kneaded, extruded, and cut by an extruder to produce pellets X having a diameter of 3 mm and a length of 3 mm.
4). Process 4
A pellet Y was produced by injection molding with an injection molding machine. As the molded body Y, public sewage and sewage joints were manufactured.

(Evaluation)
1. Injection Molded Body Appearance The appearance of the molded body Y was visually evaluated. Appearance evaluation criteria are as follows.
A: There was no surface roughness.
A: There was a slight surface roughness.
(Triangle | delta): There was the surface roughness which was conspicuous partially.
X: There were many conspicuous surface roughnesses.

2. Kneadability of the composition The raw material mixture W is melted by supplying 150 g of the raw material mixture W to a roll mill set at 180 ° C. using a roll mill (manufactured by Yasuda Seiki Seisakusho Co., Ltd., two kneading rolls for testing, 200D × 514L). The state of being kneaded and wound around a roll was observed. The evaluation criteria are as follows. This evaluation serves as an index as to whether or not the kneading in step 3 is performed uniformly in a short time, or whether or not a uniform melt is easily formed in the injection molding machine in step 4.
○: The time required for winding was 1 minute or less.
X: The time required for winding exceeded 1 minute.

3. Static Thermal Stability A sheet having a thickness of 2 mm was prepared using the composition of the raw material mixture W kneaded at 180 ° C. for 3 minutes with the roll mill. The sheet was heated with a hot press at 180 ° C., and the appearance was visually evaluated. A composition with poor evaluation is likely to cause discoloration of the molded article obtained.
A: There was no discoloration after 60 minutes.
Δ: Discoloration occurred after 60 minutes.

4). Melt viscosity of the composition The melt viscosity of the raw material mixture W was measured under the conditions of a temperature of 165 ° C. and a piston lowering speed of 100 mm / min using a capillograph (manufactured by Toyo Seiki Seisakusho, model: 1C).
5. Tensile test No. 1 dumbbell test piece was prepared by injection molding of pellet X, and the tensile strength and elongation at break were measured in accordance with JIS K7113.
6). Vicat softening temperature A test piece was prepared by injection molding of pellet X, and the Vicat softening temperature was measured according to JIS K7206.
7). Charpy impact strength A test piece was prepared by injection molding of pellet X, and Charpy impact strength was measured in accordance with JIS K7111.

The evaluation results are shown in Table 1.
Comparative Example 1 was a composition in which only a material derived from the reused raw material A was used as the vinyl chloride resin. The kneadability of the composition was poor, and the appearance of the injection molded article was poor.
Comparative Examples 2 to 4 are compositions using a vinyl chloride resin derived from the reused raw material A and one kind of vinyl chloride resin having a relatively low average degree of polymerization, and the composition has poor kneadability and injection. The appearance of the molded body was also bad.

  The waste material of the vinyl chloride resin can be effectively used as a recycled material. A rigid vinyl chloride resin composition for injection molding using a recycled vinyl chloride resin can be provided.

Claims (11)

35-80 parts by weight of recycled raw material A consisting of a hard vinyl chloride resin composition whose main component is a vinyl chloride resin having an average degree of polymerization of 900-1200 according to JIS K 6720-2, or recycled raw material A,
10 to 50 parts by weight of vinyl chloride resin B having an average degree of polymerization of 560 to 850 according to JIS K 6720-2,
Containing 3 to 25 parts by weight of vinyl chloride resin C having an average degree of polymerization of 450 to 550 according to JIS K 6720-2, and 1 to 15 parts by weight of stabilizer D,
A hard vinyl chloride resin composition for injection molding in which the total amount of the recycled material A, the vinyl chloride resin B and the vinyl chloride resin C is 100 parts by weight. Also contains 2-20 parts by weight of impact modifier E,
The hard vinyl chloride resin composition for injection molding according to claim 1. Stabilizer D is a lead compound,
The hard vinyl chloride resin composition for injection molding according to claim 1 or 2. The reuse raw material A contains a lead compound.
The hard vinyl chloride resin composition for injection molding according to claim 3. The impact resistance modifier E contains an acrylate polymer,
The hard vinyl chloride resin composition for injection molding according to any one of claims 2 to 4. Process 1 for pulverizing recycled material A to produce pulverized product V,
A process 2 for producing a raw material mixture W by mixing raw materials other than the reused raw material A and a pulverized product V, and a process 3 for producing a pellet X by heating and kneading the raw material mixture W with an extruder. The manufacturing method of the pellet which consists of the hard vinyl chloride resin composition for injection molding in any one of claim | item 1 -5. Process 1 for pulverizing recycled material A to produce pulverized product V,
Step 2 of mixing raw materials other than the recycled raw material A and the pulverized product V to produce a raw material mixture W,
The process 3 of heating and kneading | mixing the raw material mixture W with an extrusion molding machine and manufacturing the pellet X, and the process 4 of injection-molding the pellet X with an injection molding machine and manufacturing the molded object Y of Claims 1-5 are provided. The manufacturing method of the molded object which consists of the hard vinyl chloride resin composition for injection molding in any one.   The molded object obtained by the method of Claim 7.   The molded body according to claim 8, which is a metal or a joint.   It consists of the hard vinyl chloride resin composition for injection molding in any one of Claims 1-5.   A joint comprising the hard vinyl chloride resin composition for injection molding according to any one of claims 1 to 5.