JP2015199311A - Laminated sheet and container using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated sheet excellent in notch breaking properties, impact resistance, and moldability as compared with a conventional high-impact polystyrene-based sheet, and to provide a container excellent in rigidity manufactured using the laminated sheet.SOLUTION: The laminated sheet is used which comprises a core layer mainly composed of a mixture of high-impact polystyrene and polystyrene, and outer layers disposed on both surfaces of the core layer and mainly composed of high-impact polystyrene. The ratio of the thickness of the core layer to the total thickness is 70-95%, the amount of polybutadiene in the core layer is 1-5 mass%, and the amount of polybutadiene in the outer layers is 6-10 mass%.

Description

The present invention relates to a laminated sheet and a container using the same.

Since a sheet or film mainly composed of polystyrene is excellent in molding processability, it has been widely used for various packaging materials such as food containers, beverage containers, and industrial containers including various trays. In addition, a sheet having excellent impact resistance is widely used by using high impact polystyrene obtained by graft copolymerization of polystyrene with polybutadiene. In recent years, cases where these containers are manufactured by an integrated process of molding, filling of contents, and sealing of lid materials have been increasing (Patent Documents 1 and 2).
Although these sheets have increased toughness and improved impact resistance as the polybutadiene content increases, there is a problem that rigidity and notch breakability after molding are lowered.
In order to solve this problem, for example, in a laminated sheet having a tough polyolefin-based resin layer, the polyolefin-based resin layer is arranged in the vicinity of the outermost layer on the notch molding surface side of the sheet, and the layer is completely formed at the same time as the notch is made A method for securing notch folding performance by cutting the film into two is proposed (Patent Document 3). However, there are various ways to insert the notches, and there are a method of notching in a straight line and a method of notching in a broken line. Since there is a region where the olefin-based resin layer is not completely cut off, it is difficult to develop good notch breakability. Thus, it has been difficult for the conventional technology to achieve both rigidity, notch breakability and impact resistance.

JP 2011-51264 A Japanese translation of PCT publication No. 2003-522052 JP 2007-55266 A

An object of this invention is to provide the laminated sheet which is excellent in notch bendability, impact resistance, and a moldability in view of the said problem and the situation. Furthermore, it aims at providing the container excellent in the rigidity shape | molded using this laminated sheet.

The present invention for solving the above-described problems is constituted as follows.
(1) A laminated sheet consisting of a middle core layer mainly composed of a mixture of high impact polystyrene and polystyrene and an outer layer mainly composed of high impact polystyrene disposed on both sides of the middle core layer. The ratio of the thickness of the inner core layer to 70 to 95%, the amount of polybutadiene in the inner core layer is 1 to 5% by mass, and the amount of polybutadiene in the outer layer is 6 to 10% by mass. Characteristic laminated sheet.
(2) The laminated sheet according to (1), wherein the volume average particle diameter of the polybutadiene is 2 to 4 μm.
(3) The laminated sheet according to (1) or (2), wherein a melt mass flow rate at 200 ° C. and 5 kgf load of the outer layer and the middle core layer is 2 to 20 g / 10 minutes.
(4) The laminated sheet according to any one of (1) to (3), wherein the total thickness is 0.5 to 1.0 mm.
(5) A molded container using the laminated sheet according to any one of (1) to (4).
(6) The molded container according to (5), which is a container for yogurt produced by an in-line method.

In the present invention, in a laminated sheet comprising a core layer mainly composed of a mixture of high-impact polystyrene and polystyrene, and an outer layer mainly composed of high-impact polystyrene disposed on both sides of the core layer, the outer layer with respect to the total thickness It was found that a laminated sheet excellent in notch folding property, impact resistance and moldability can be obtained by setting the thickness of the polybutadiene in the core layer and the amount of polybutadiene in the outer layer within a specific range. In addition, a molded container using the laminated sheet of the present invention is excellent in rigidity.

The notch in the present specification means a wedge-shaped cut formed in a container connecting portion in order to separate individual containers from a series of yogurt molded containers by press-molding a laminated sheet. When separating the container, it is necessary to easily break the connecting portion by folding the connecting portion into a valley or a mountain.
The container produced by the in-line method in the present invention is a production method that consistently performs a series of steps from container molding, contents filling, and sterilization used in a molding process of a yogurt container or the like.

The laminated sheet of the present invention was disposed on both sides of a core layer having a polybutadiene content of 1 to 5% by mass based on a mixture of high impact polystyrene (hereinafter abbreviated as HIPS) and polystyrene. It is comprised from the outer layer which has 6-10 mass% polybutadiene as a main component.

<Core layer>
The core layer of the present invention is mainly composed of a mixture of HIPS and polystyrene. The amount of polybutadiene contained in the middle core layer is 1 to 5% by mass, and more preferably 3 to 4% by mass. If the amount of polybutadiene is less than 1%, impact resistance may be reduced, and if it exceeds 5% by mass, the elongation at break of the core layer is increased, so that notch breakability may be reduced.

HIPS shows a form in which polystyrene chains are grafted onto polybutadiene chains. Examples of the polybutadiene chain include a polybutadiene homopolymer, a random copolymer of styrene and butadiene, and a block copolymer of styrene and butadiene.

In the polystyrene chain of HIPS, non-diene monomer components such as α-methylstyrene, methyl methacrylate, methyl acrylate, methacrylic acid, acrylic acid, maleic anhydride, acrylonitrile and the like are not impaired. May be copolymerized. As a method for graft polymerization, known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization can be employed. In addition, a small amount of a crosslinking agent such as divinylbenzene may be added during polymerization to polymerize, mineral oil, rosin ester, terpene resin, higher fatty acid, higher fatty acid salt, higher fatty acid amide, antioxidant, ultraviolet absorber, Additives such as antistatic agents can also be included. In addition, HIPS may use together 2 or more types of HIPS from which molecular weight and fluidity differ.

The polystyrene used for the core layer means polystyrene made of a homopolymer of styrene. The weight average molecular weight of polystyrene is preferably 150,000 to 430000, more preferably 300000 to 400000, from the viewpoint of impact resistance. If the weight average molecular weight exceeds 430000, the moldability may decrease. The weight average molecular weight of polystyrene can be adjusted by a polymerization initiator, a polymerization temperature, or the like.

If the amount of polybutadiene in the core layer is 1 to 5% by mass, a resin other than HIPS and polystyrene can be used. Examples of resins other than HIPS and polystyrene that can be blended in the middle core layer include polymers such as methyl methacrylate-styrene copolymer, acrylonitrile-styrene copolymer, and block copolymer of styrene and butadiene.

The volume average particle diameter of the polybutadiene of HIPS used for the middle core layer is preferably 2 to 4 μm, and more preferably 2.7 to 3.6 μm. If the volume average particle size is less than 2 μm, impact resistance may be reduced, and if it exceeds 4 μm, the breaking elongation of the inner layer increases, and notch breakability may be reduced.

As long as the effect of the present invention is not impaired, the core layer has a colorant such as a pigment and a dye, a release agent such as silicone oil and higher fatty acid ester, a fibrous reinforcing material such as glass fiber, talc, clay and silica. Components such as a filler, an antistatic agent such as an alkali metal sulfonate and a polyalkylene glycol, an antioxidant, an ultraviolet absorber and an antibacterial agent can be added.

The melt mass flow rate (hereinafter abbreviated as MFR) at 200 ° C. and 5 kgf load of the core layer is preferably 2 to 20 g / 10 minutes. If it is less than 2 g / 10 minutes, the fluidity is lowered and residual stress is likely to be generated in the molded container, so that the container may be broken by contact with chemicals or the like. Moreover, when it exceeds 20 g / 10 minutes, the thickness uniformity of a shaping | molding container may fall and rigidity may fall.
In addition, MFR in this invention shows the numerical value measured by 200 degreeC and 5 kgf load unless there is a notice.

The ratio of the thickness of the core layer to the total thickness is 70 to 95%, preferably 80 to 90%. If the ratio of the thickness of the core layer to the total thickness is less than 70%, the notch breakability may be lowered. Moreover, when it exceeds 95%, impact resistance may fall.

<Outer layer>
The outer layer of the present invention is mainly composed of HIPS. The amount of polybutadiene contained in the outer layer is 6 to 10% by mass, and more preferably 7 to 9% by mass. If the amount of polybutadiene is less than 6% by mass, the impact resistance may decrease, and if it exceeds 10% by mass, the elongation at break of the middle core layer increases, and the notch foldability may decrease.

If the amount of polybutadiene in the outer layer is 6 to 10% by mass, a resin other than HIPS can be used. Examples of these resins include polymers such as polystyrene, methyl methacrylate-styrene copolymer, acrylonitrile-styrene copolymer, and block copolymer of styrene and butadiene.

The volume average particle size of the polybutadiene in the outer layer is preferably 2 to 4 μm, and more preferably 2.5 to 3 μm. If the volume average particle diameter is less than 2 μm, impact resistance may be reduced, and if it exceeds 4 μm, the fracture elongation of the outer layer increases, and notch breakability may be reduced.

As long as the effects of the present invention are not impaired in the outer layer, colorants such as pigments and dyes, mold release agents such as silicone oil and higher fatty acid esters, fibrous reinforcing materials such as glass fibers, talc, clay and silica. Components such as a filler, an alkali metal sulfonate, an antistatic agent such as polyalkylene glycol, an antioxidant, an ultraviolet absorber, and an antibacterial agent can be added.

The MFR of the outer layer at 200 ° C. and 5 kgf load is preferably 2 to 20 g / 10 minutes, and more preferably 3 to 10 g / 10 minutes. If it is less than 2 g / 10 minutes, the fluidity is lowered and residual stress is likely to be generated in the molded container, so that the container may be broken by contact with chemicals or the like. Moreover, when it exceeds 20 g / 10 minutes, the thickness uniformity of a shaping | molding container may fall and rigidity may fall.

The total thickness is preferably 0.5 to 1.0 mm, more preferably 0.6 to 0.8 mm. If the total thickness of the laminated sheet is less than 0.5 mm, the rigidity at the time of container molding may be reduced. If it is thicker than 1 mm, the additive in the core layer may bleed or bloom on the surface.

In the laminated sheet of the present invention, the 50% fracture height of the DuPont impact strength defined by ASTM D2794 preferably has an impact resistance of 1.0 J or more, and more preferably 1.5 J or more. Since the impact resistance is poor at less than 1.0 J, the container may be damaged when the container is molded.

The production method of the laminated sheet of the present invention is not particularly limited, and sheets for forming the core layer and the outer layer are formed by extrusion molding such as an inflation method or a T-die method, and these sheets are laminated by thermal lamination. Can be manufactured.
As another method, the resin for forming the core layer and the outer layer is supplied to separate extruders, melt-kneaded and supplied to the feed block, and then the laminated sheet is formed by a melt coextrusion method through a T-die. It can also be obtained by a manufacturing method. Moreover, it can also be manufactured by supplying a melt-kneaded resin to a multi-layer manifold die having a three-layer structure to manufacture a multilayer sheet. This manufacturing method is preferable in that a sheet having a small thickness distribution of each layer can be obtained. When each resin is melted and each layer is obtained by extrusion molding, the temperature of each resin during molding is preferably 130 ° C to 260 ° C.
Further, the laminated sheet can be subjected to longitudinal stretching (stretching in the production direction) and lateral stretching (stretching in a direction orthogonal to longitudinal stretching) using a roll speed difference, a tenter stretching machine, or the like, if necessary. .

The laminated sheet of the present invention can be formed into various containers by known thermoforming methods such as vacuum forming, pressure forming, vacuum / pressure forming, press forming, hot plate forming, and the like. The container using the laminated sheet of the present invention can be suitably used for various containers such as food containers, beverage containers, pharmaceutical containers, and daily necessities containers, but is particularly suitable for yogurt containers produced in an in-line manner.

As an in-line molding method, a method of heating the sheet with a hot plate after feeding out the laminated sheet, molding the sheet into a predetermined shape by vacuum / compressed air, and filling the contents can be employed.

The molded container using the laminated sheet of the present invention performs compression measurement as defined by JIS-K7181, and preferably has a buckling strength of 60 N or more, more preferably 70 N or more. If it is less than 60 N, the buckling strength is excessively lowered, and the molded container may be damaged.

EXAMPLES Hereinafter, although an Example demonstrates this invention, these Examples do not limit this invention.
[Example 1]
<Resin forming the core layer>
40 parts by mass of Toyo Styrene Co., Ltd. HIPS “Toyostyrene H850N” (polybutadiene volume average particle size = 2.8 μm, polybutadiene amount = 9.0% by mass, MFR = 3.6 g / 10 min), Toyo Styrene Co., Ltd. ) Use a mixture of 60 parts by mass of polystyrene “Toyostyrene G200C” (MFR = 8.5 g / 10 min) manufactured by Toshiba Machine Co., Ltd. (screw diameter φ65 mm, L / D = 28.8). Then, the resin was supplied to a T-die feed block at a resin temperature of 220 ° C.

<Resin forming the outermost layer>
HIPS “Toyostyrene H850N” (polybutadiene amount = 9.0% by mass, MFR = 3.6 g / 10 min) manufactured by Toyo Styrene Co., Ltd. was used as a single-screw extruder manufactured by Frontier Corporation (screw diameter φ 40 mm, L / D = 25.9) and fed to the feed block of the T die at a resin temperature of 220 ° C.

<Multilayer sheet>
The resin forming the center layer and the outer layer supplied to the feed block was molded into a two-layer / three-layered sheet of outer layer / medium core layer / outer layer at 220 ° C. using a straight-type T-die having a width of 550 mm. The extruded sheet was pressure-bonded to an 80 ° C. cast roll and cooled, and further cooled to room temperature to obtain a laminated sheet. The results are shown in Table 1.

Evaluation of this invention followed the following method.
(Polybutadiene content)
The used HIPS was dissolved in chloroform, and iodine monochloride was added to react with the double bond in polybutadiene. The amount of polybutadiene was determined by adding potassium iodide to the remaining iodine monochloride and converting it into iodine, which was then subjected to reverse titration with sodium thiosulfate. The amount of polybutadiene in the middle core layer and in the outer layer was calculated based on the amount of HIPS used for blending each layer.

(Volume average particle diameter of polybutadiene)
The HIPS used was dispersed in dimethylformamide at a concentration of 2% by mass and further dispersed for 20 minutes with an ultrasonic bath. This was dropped into a laser commentary scattering method particle size distribution measuring device “LS-230” manufactured by Beckman Coulter Co., Ltd., which had been filled with dimethylformamide, and the volume average particle size was determined by a slater diffraction scattering method.

(Thickness of the core layer)
A 1-m laminated sheet was cut out, and 20 mm square sections were cut out from the left and right ends and the center in the direction perpendicular to the production direction. After smoothing the end face, the thickness of the core layer of each of the three sections was measured with a microscope “VK-X100” manufactured by Keyence Corporation. The laminated sheet was cut out and the thickness of the central layer was measured three times in total, and the arithmetic average value of the thickness of the nine core layers was defined as the thickness of the core layer.

(Total thickness of laminated sheet)
A 1 m laminated sheet was cut out, 20 mm square sections were cut out from the right and left ends and the center in the direction perpendicular to the production direction, and the total thickness of the laminated sheet was measured using a micrometer. Cutout of the laminated sheet and measurement of the total thickness were performed three times in total, and the arithmetic average value of the total thickness of 9 points was defined as the total thickness.

(Measurement of melt mass flow rate)
Based on JIS K-7210, it measured by 200 degreeC and 5 kgf load.

(Formability of laminated sheet)
A 1 m laminated sheet was cut out and the appearance of the sheet surface was visually observed to evaluate the formability of the sheet by the following determination.
Good: No whitening phenomenon such as melt fracture or delamination occurred on the surface of the molded sheet.
Possible: 1 to 5 whitening phenomena such as melt fracture and delamination occur on the surface of the molded sheet.
Defect: The molded sheet has 6 or more whitening phenomena such as melt fracture and delamination on the entire surface.

(DuPont impact strength)
Using a DuPont impact tester (B-351000601 manufactured by Toyo Seiki Co., Ltd.), the DuPont impact strength of the obtained laminated sheet was measured. The measurement was performed according to ASTM D2794, using a striker with a tip radius of 7.9 mm in an environment of 23 ° C. and 50% relative humidity. The measured values were judged as superior or inferior according to the following criteria.
Good: DuPont impact strength is 1.5 J or more.
Good: DuPont impact strength is 1.0 J or more and less than 1.5 J.
Defect: DuPont impact is less than 1.0J.

(Container moldability)
With a single vacuum forming machine (manufactured by Asano Laboratories), the opening diameter is 50 mm, the bottom diameter is 50 mm, and the height is 50 mm. Side face thickness: 10% to 30% of the total sheet thickness, bottom face thickness: sheet A cup-shaped molded container having a total thickness of 25% to 40% was molded. The hot platen temperature was 600 ° C. and the molding time was 20 seconds. The appearance of the container, the bottom surface, and the corner (portion where the bottom surface and the outside contact) was visually observed and evaluated according to the following criteria.
Good: Uniformly stretched and formed to a uniform thickness.
Possible: Uneven thickness at the bottom or part of the corner.
Defective: There is a tear at the bottom or part of the corner.

(Buckling strength of container)
Using a laminated sheet, with a single vacuum forming machine (manufactured by Asano Laboratory Co., Ltd.), the opening diameter is 50 mm, the bottom surface diameter is 50 mm, the height is 50 mm, and the side surface thickness is 10% to 30% of the total sheet thickness, the bottom surface Part thickness: A cup-shaped molded container having a thickness of 25% to 40% of the total thickness of the sheet was molded. The hot platen temperature was 600 ° C. and the molding time was 20 seconds.
The buckling strength of the obtained molded container was measured in an environment of 23 ° C. and 50% relative humidity. The buckling strength was the maximum point load when compression measurement was performed according to JIS-K7181. The measurement equipment, compression conditions, and criteria for buckling strength are described below.
Equipment used: Strograph VEID (manufactured by Toyo Seiki Co., Ltd.)
Compression speed: 50 mm / min
Judgment criteria:
Good: Buckling strength is 70 N or more.
Good: Buckling strength is 60N or more and less than 70N.
Defect: Buckling strength is less than 60N.

(Notch foldability of container)
A 50 mm square test piece was sampled from the center of the sheet, and a notch was formed by making a cut at a depth of 50% with respect to the sheet thickness on a diagonal line from one apex to the other apex. The notch foldability was evaluated according to the following criteria based on the presence or absence of breakage when the notched surface was bent 150 degrees in an environment of 23% relative humidity 50%.
Good: Fracture occurred from the notch portion by the first folding.
Defect: The first fold did not cause breakage from the notch.

[Example 2]
A laminated sheet was formed in the same manner as in Example 1 except that the thickness ratio of the core layer to all layers was changed to 83%. The results are shown in Table 1.

[Example 3]
A laminated sheet was formed in the same manner as in Example 1 except that the thickness ratio of the core layer to all layers was changed to 93%. The results are shown in Table 1.

[Example 4]
The outer layer resin is 63 parts by mass of HIPS “Toyostyrene H850” manufactured by Toyo Styrene Co., Ltd. (polybutadiene volume average particle size = 2.5 μm, polybutadiene amount = 9.8% by mass, MFR = 3.6 g / 10 min). A laminated sheet was formed in the same manner as in Example 1 except that the content was changed to 37 parts by mass of polystyrene “Toyostyrene G200C”. The results are shown in Table 1.

[Example 5]
A laminated sheet was formed in the same manner as in Example 1 except that the resin of the outer layer was changed to 72 parts by mass of HIPS “Toyostyrene H850” manufactured by Toyo Styrene Co., Ltd. and 28 parts by mass of polystyrene “Toyostyrene G200C”. The results are shown in Table 1.

[Example 6]
A laminated sheet was formed in the same manner as in Example 1 except that the resin of the outer layer was changed to 90 parts by mass of HIPS “Toyostyrene H850” manufactured by Toyo Styrene Co., Ltd. and 10 parts by mass of polystyrene “Toyostyrene G200C”. The results are shown in Table 1.

[Example 7]
A laminated sheet was formed in the same manner as in Example 1 except that the resin in the outer layer was changed to HIPS “Toyostyrene H850” manufactured by Toyo Styrene Co., Ltd. The results are shown in Table 1.

[Example 8]
A laminated sheet was formed in the same manner as in Example 1 except that the resin of the core layer was changed to a mixture of 15 parts by mass of HIPS “Toyostyrene H850N” and 85 parts by mass of polystyrene “Toyostyrene G200C”. The results are shown in Table 1.

[Example 9]
A laminated sheet was formed in the same manner as in Example 1, except that the resin of the core layer was changed to a mixture of 30 parts by mass of HIPS “Toyostyrene H850N” and 70 parts by mass of polystyrene “Toyostyrene G200C”. The results are shown in Table 1.

[Example 10]
A laminated sheet was formed in the same manner as in Example 1, except that the resin of the core layer was changed to a mixture of 40 parts by mass of HIPS “Toyostyrene H850N” and 60 parts by mass of polystyrene “Toyostyrene G200C”. The results are shown in Table 1.

[Example 11]
A laminated sheet was formed in the same manner as in Example 1 except that the resin of the core layer was changed to a mixture of 50 parts by mass of HIPS “Toyostyrene H850N” and 50 parts by mass of polystyrene “Toyostyrene G200C”. The results are shown in Table 1.

[Comparative Example 1]
A laminated sheet was formed in the same manner as in Example 1 except that the thickness ratio of the core layer to the entire layer was changed to 96%, but the resulting laminated sheet had low Dupont impact strength. The results are shown in Table 2.

[Comparative Example 2]
A laminated sheet was formed in the same manner as in Example 2 except that the thickness ratio of the core layer to the entire layer was changed to 68%. The resulting laminated sheet was inferior in notch foldability. The results are shown in Table 2.

[Comparative Example 3]
The outer layer resin is 80 parts by mass of HIPS “Toyostyrene XL1” (polybutadiene volume average particle diameter = 0.6 μm, polybutadiene content = 13.4% by mass, MFR = 2.6 / 10 min) manufactured by Toyo Styrene Co., Ltd. A laminated sheet was formed in the same manner as in Example 1 except that the mixture was changed to a mixture of 20 parts by mass of polystyrene “Toyostyrene G200C”. The resulting laminated sheet had poor notch folding properties. The results are shown in Table 2.

[Comparative Example 4]
The laminated sheet was formed in the same manner as in Example 1 except that the outer layer resin was changed to a mixture of 65 parts by mass of HIPS “Toyostyrene H850N” and 35 parts by mass of polystyrene “Toyostyrene G200C”. The laminated sheet had a poor DuPont impact strength. The results are shown in Table 2.

[Comparative Example 5]
The laminated sheet was molded in the same manner as in Example 1 except that the resin of the core layer was changed to a mixture of 10 parts by mass of HIPS “Toyostyrene H850N” and 90 parts by mass of polystyrene “Toyostyrene G200C”. The resulting laminated sheet had a low DuPont impact strength. The results are shown in Table 2.

[Comparative Example 6]
The laminated sheet was molded in the same manner as in Example 1 except that the resin of the core layer was changed to a mixture of 60 parts by mass of HIPS “Toyostyrene H850N” and 40 parts by mass of polystyrene “Toyostyrene G200C”. The obtained laminated sheet was inferior in notch foldability. The results are shown in Table 2.

From the results of Tables 1 and 2, by using the laminated sheet of the present invention, compared to the conventional high impact polystyrene sheet, it maintains rigidity, molding processability, notch folding performance, and excellent impact resistance. It is realized and can be suitably used for various containers including yogurt containers.

The laminated sheet of the present invention maintains rigidity, moldability, notch folding performance, and is excellent in impact resistance, so that it is suitably used as a yogurt container, and other food containers, beverage containers, pharmaceutical containers, daily necessities containers, etc. It can be used for various applications such as various containers.

Claims (6)

A laminated sheet composed of a high-impact polystyrene and a mixture of polystyrene as a main component, and an outer layer mainly composed of a high-impact polystyrene disposed on both sides of the core layer, wherein The thickness ratio of the core layer is 70 to 95%, the amount of polybutadiene in the middle core layer is 1 to 5% by mass, and the amount of polybutadiene in the outer layer is 6 to 10% by mass. Laminated sheet. The laminated sheet according to claim 1, wherein the volume average particle diameter of the polybutadiene is 2 to 4 μm. The laminated sheet according to claim 1 or 2, wherein the outer layer and the core layer have a melt mass flow rate of 2 to 20 g / 10 min at 200 ° C and a load of 5 kgf. 4. The laminated sheet according to claim 1, wherein the total thickness is 0.5 to 1.0 mm. The shaping | molding container using the lamination sheet as described in any one of Claims 1-4. The molded container according to claim 5, which is a container for yogurt produced in an in-line manner.